May 23, 2025
(the code used is available at https://github.com/csdurfee/nfl_combine_data/).
Intro
Every year, the National Football League hosts an event called the Combine, where teams can evaluate the top prospects before the upcoming draft.
Athletes are put through a series of physical and mental tests over the course of four days. There is a lot of talk of hand size, arm length, and whether a guy looks athletic enough when he's running with his shirt off. It's basically the world's most invasive job interview.
NFL teams have historically put a lot of stock in the results of the combine. A good showing at the combine can improve a player's career prospects, and a bad showing can significantly hurt them. For that reason, some players will opt out of attending the combine, but that can backfire as well.
I was curious about which events in the combine correlate most strongly with draft position. There are millions of dollars at stake. The first pick in the NFL draft gets a $43 Million dollar contract, the 33rd pick gets $9.6 Million, and the 97th pick gets $4.6 Million.
The main events of the combine are the 40 yard dash, vertical leap, bench press, broad jump, 3 cone drill and shuttle drill. The shuttle drill and the 3 cone drill are pretty similar -- a guy running between some cones as fast as possible. The other drills are what they sound like.
I'm taking the data from Pro Football Reference. Example page: https://www.pro-football-reference.com/draft/2010-combine.htm. I'm only looking at players who got drafted.
Position Profiles
It makes no sense to compare a cornerback's bench press numbers to a defensive lineman's. There are vast differences in the job requirements. A player in the combine is competing against other players at the same position.
The graph shows a position's performance on each exercise relative to all players. The color indicates how the position as a whole compares to the league as a whole. You can change the selected position with the dropdown.
Cornerbacks are exceptional on the 40 yard dash and shuttle drills compared to NFL athletes as a whole, whereas defensive linemen are outliers when it comes high bench press numbers, and below average at every other event. Tight Ends and Linebackers are near the middle in every single event, which makes sense because both positions need to be strong enough to deal with the strong guys, and fast enough to deal with the fast guys.
Importance of Events by Position
I analyzed how a player's performance relative to others at their position correlates with draft rank. Pro-Football-Reference has combine data going back to 2000. I have split the data up into 2000-2014 and 2015-2025 to look at how things have changed.
For each position, the exercises are ranked from most to least important. The tooltip gives the exact r^2 value.
Here are the results up to 2014:
Here are the last 10 years:
Some things I notice:
The main combine events matter that much either way for offensive and defensive linemen. That's held true for 25 years.
The shuttle and 3 cone drill have gone up significantly in importance for tight ends.
Broad jump and 40 yard dash are important for just about every position. However, the importance of the 40 yard dash time has gone down quite a bit for running backs.
As a fan, it used to be a huge deal when a running back posted an exceptional 40 yard time. It seemed Chris Johnson's legendary 4.24 40 yard time was referenced every year. But I remember there being lot of guys who got drafted in the 2000's primarily based on speed who turned out to not be very good.
The bench press is probably the least important exercise across the board. There's almost no correlation between performance and draft order, for every position. Offensive and defensive linemen basically bench press each other for 60 minutes straight; for everybody else, that sort of strength is less relevant. Here's one of the greatest guys at throwing the football in human history, Tom Brady:
Compared to all quarterbacks who have been drafted since 2000, Brady's shuttle time was in the top 25%, his 3 cone time was in the top 50%, and his broad jump, vertical leap and 40 yard dash were all in the bottom 25%.
Changes in combine performance over time
Athlete performance has changed over time.
I've plotted average performance by year for each of the events. For the 40 yard dash, shuttle, and 3 cone drills, lower is better, and for the other events, higher is better.
40 yard dash times and broad jump distances have clearly improved, whereas shuttle times and bench press reps have gotten slightly worse.
There's a cliche in sports that "you can't coach speed". While some people are innately faster than others, the 40 yard dash is partly a skill exercise -- learning to get off the block as quickly as possible without faulting, for starters. The high priority given to the 40 yard dash should lead to prospects practicing it more, and thus getting better numbers.
The bench press should be going down or staying level, since it's not very important to draft position.
There's been a significant improvement in the broad jump - about 7.5% over 25 years. As with the 40 yard dash, I'd guess it's better coaching and preparation. Perhaps it's easier to improve than some of the other events. I don't think there's more broad jumping in an NFL game than there was 25 years ago.
Shuttle times getting slightly worse is a little surprising. It's very similar to the 3 Cone drill, which has slightly improved. But as we saw, neither one is particularly important as far as draft position, and it's not a strong trend.
Caveats
Some of the best athletes skip the combine entirely, because their draft position is already secure. And some athletes will only choose to do the exercises they think they will do well at, and skip their weak events. This is known as MNAR data (missing, not at random). All analysis of MNAR data is potentially biased.
I'm assuming a linear relationship between draft position and performance. It's possible that a good performance helps more than a bad performance hurts, or vice versa.
I didn't calculate statistical significance for anything. Some correlations will occur even in random data. This isn't meant to be rigorous.
Jul 12, 2025
Earlier this year, I wrote most of a book about the psychology and mathematics of sports gambling called Your Parlay Sucks. The book never quite came together, and is probably too weird to ever get published, but it has some interesting bits, so I figured I'd share them here.
Why did I get interested enough in sports betting to write a whole book about it? I think it's because I'm fascinated by the limits of rationality. Philosophers, economists and social scientists would like to treat humans as though they are capable of making rational decisions. That conflicts with the real world, where even pretty smart people make irrational choices. I certainly have.
Sports betting is a sort of rationality lab. You and I might have different values or beliefs. What's crazy to me might be normal to you, or vice versa, but we should both be able to agree that placing bets that are guaranteed to lose money is irrational.
This paper, "Intuitive Biases in Choice versus Estimation", is a wonderful illustration of cognitive bias and irrationality in the realm of sports betting.
The researchers had people bet on NFL football against the point spread. If you're not familiar, the idea behind the point spread is to attract an equal amount of action on both sides of the bet by handicapping one of the teams. If you bet on the favorite, they need to win by at least the amount of the spread for the bet to win. The other side side wins if the team loses by less than the spread, or wins the game outright.
Gamblers can bet either side, and if there are more bets on one side than the other, the sportsbook can change the spread to attract equal action. So there's a potential for the wisdom of crowds to kick in, the invisible hand of the market moving the line towards the best estimate possible.
Of course, that depends on gamblers being rational. A rational gambler has to be willing to take either side of a bet (or not bet at all), depending on the spread. If the spread is biased towards the underdog, they should be willing to take the underdog. If it's biased towards the favorite, they should take the favorite. And if the line is perfectly fair, they shouldn't bet at all.
As I showed a while back with ensemble learning, the wisdom of crowds only works if the errors that people make are uncorrelated with each other. If most people are wrong about a particular thing, the "wisdom of crowds" will be wrong, too.
This study found that people are consistently irrational when it comes to point spreads. They will tend to bet the favorite, even though both sides should have an equal chance of winning. It's probably easier to focus on which team is better, and assume that the better team is more likely to win against the point spread as well. It's harder to imagine the underdog losing the game but winning the bet, or pulling an upset and winning outright.
The study took things further and adjusted the lines to be biased against the favorite team, so that taking the favorite would be guaranteed to lose more than 50% of the time. They even told the gamblers that they did this. And the gamblers still overwhelmingly picked the favorites. The researchers continued the study for the whole season. Even after weeks and weeks of steadily losing, being told over and over that the lines are unfair, the gamblers still preferred to take the favorites. They never learned. The participants got to keep their winnings, so they had an incentive to be right. And they still couldn't do it.
Sportsbooks have a lot of ways of trick people into taking extra bad bets, as I will show. But they don't really need to. People will consistently take bad bets even if they should know they're bad bets.
Nov 07, 2025
Song: Charlie Musselwhite, "Cristo Redentor"
Are betting experts any good at what they do?
These days, nearly all talk about gambling I see on TV and the internet is sponsored by one of the sportsbooks. How good is all this sponsored advice?
There are quite a few shows that are just about gambling, but more common are ad reads from Youtubers or sportscasters who are sponsored by sportsbooks, but aren't really focused on gambling. These appear on-air in the middle of a game, or an ad break in a Youtube video.
Picks from sports announcers do terribly, as the Youtube channel Foolish Baseball has documented in their wonderful video, Baseball is Ruining Gambling.
As a numbers guy, it's baffling that anybody would follow these obviously sponsored picks at obviously juiced lines, given by obviously casual gamblers, but some people are taking them, because the sportsbooks keep paying for the ads.
Gambling is a social and parasocial activity now, another thing you do on your phone when you're bored that sort of feels like interacting with other humans, but isn't.
Some gamblers want to be on the same side of the bet as their favorite YouTuber, who give their favorite picks as a part of an ad read. The apps also allow you to follow people, and take the same bets they take. It's yet another one-way online relationship.
Other gamblers take bets to feel more connected to their team. Announcer parlays are invitations to take a financial interest in the game that you're already watching, not necessarily because you think the Brewers play-by-play guy is secretly a betting wizard. The baseball announcers don't seem to have much of an interest in gambling, or being touts. They're not there for our wholesome national pastime, gambling on sports, they're true sickos who are only interested the disreputable game of baseball. Putting together some half-ass parlay for the promo is part of their job. It's just another ad read. It may as well be a local roofing company or a personal injury lawyer.
Sportsbooks advertise because it makes them money in the long run. These companies seem pretty well-run, if nothing else. They want to sponsor people who are good at bringing in customers with a high Customer Lifetime Value -- people who will lose over and over again for years, making back the cost to acquire them as a customer many times over. That's it. That's the game. Why would they sponsor people who give good advice about gambling, or good picks?
Do people care whether gambling experts are actually good or not?
Some guys talk about gambling for a living. They discuss sports from the perspective of people who are gamblers first, and sports fans second. Everything's an angle, or a trend, or a bad beat. At the extreme, athletic competitions are interesting because betting on them is interesting, not because sports themselves are. These guys are both living and selling the gambling lifestyle, which I talk much more about in the book:
A parasocial relationship with a guy selling picks or talking about gambling on a podcast causes guys to want to form social relationships around gambling. They're Gambling Guys now. Which leads to an endless parade of dudes complaining about their parlays online, and, I would wager, annoying the heck out of their significant others. "It's a whole lifestyle, Sherri! Of course I had to get my tips frosted! I'm a Gambling Guy now!"
It's all imaginary. An imaginary relationship with a betting guru in the form of a "hot tip". An imaginary relationship with the sporting event or player in the form of a bet. An imaginary relationship with reality itself in the form of the rationalization about why the "hot tip" didn't win. An imaginary relationship between winning and skill.
Being a sports fan is already ridiculous enough.
Poking the bear, a bit
The Ringer is a website about sports and pop culture that has evolved into a podcasting empire. I like a lot of what they do, and I especially appreciate that they publish great writing that surely isn't profitable for the company. For the most part, I can just enjoy their non-gambling content and ignore that it's subsidized by gambling.
But they've done as much as anyone to normalize sports betting as a lifestyle, and deserve an examination of that. The Ringer wasn't worth a bajillion dollars before gambling legalization, back when they were doing MeUndies ad reads.
The Ringer has an incredible amount of content that's just Gambling Guys Talk Gambling with Other Gambling Guys, around 10 hours a week of podcasts, by my count. The Ringer's flagship show is the Bill Simmons Podcast, which usually devotes at least a couple hours a week to discussing which bets Bill and his pals think are good. (Previously satirized in Cool Parlay, Bro)
The site also has an hour long daily podcast about gambling, The Ringer Gambling Show, and several other podcasts that regularly discuss betting. As far as I know, all of their sports podcasts feature gambling ad reads, even the ones with hosts that clearly find gambling distasteful.
Several members of the Ringer's staff are full time Gambling Guys now. They talk about their addictions for a living, which must be nice. I've been talking about my crippling data science addiction on here for months without a single job offer.
Are these guys good at their job, though? (Are they good at their addictions?) The Ringer is currently having a contest betting on the NFL between five different NFL podcasts, four of which primarily cover sports gambling, which they're calling The Ringer 107. Here are their results through Week 9:
Every single one of the five teams is losing money against the spread. They don't make it clear on the website, but some bets are at -120 vig, so the records are even worse than they look.
It might be bad luck, right? I've written at length about how having a true skill level of 55% doesn't guarantee actually winning 55% of the bets.
Based on this data, it's extremely unlikely the gambling pros at the Ringer are just unlucky. I simulated 5 teams taking the same number of bets as the Ringer's contest so far. If every pick had a 55% chance of winning (representing picks by advantage players), then 99.5% of the time, at least one team does better than all five of the Ringer's did.
Even at a 50% winning rate, same as flipping a coin, the simulation does better than the Ringer 91% of the time. Based on this data, you'd be better off flipping a coin than listening to these gambling experts.
The easiest way to know they can't do it
If I talked about gambling for a living and was demonstrably good at it, I'd want everyone to see the proof. These guys almost never post their actual records over a long stretch of time, though. They will crow about their wins, and offer long-winded explanations as to why their losing picks were actually right, and reality was wrong. But it's hard to find actual win-loss records for them.
Last season, The Ringer's Anthony Dabbundo didn't appear to keep track of his record betting on the NFL against the spread at all (example article). This year, he has, so we know he's gone 37-37, and 20-25 on his best bets, despite some of them being at worse than -110 odds. His best bets have had a return of -16.7%, about the same as lazy MLB announcer parlays, and almost 4 times worse than taking bets by flipping a coin.
What odds would you give me that the Ringer goes back to not showing his record next season?
To be clear, I don't think Dabbundo is worse than the average gambling writer at gambling. I've never found a professional Gambling Guy that is statistically better than a coin flip. Dabbundo's job is writing/podcasting the little descriptions that go along with each of his picks. His job isn't being good at gambling, it's being good at talking about gambling. There is no evidence that he can predict the future but plenty of evidence he can crank out an hour of podcast content every weekday that enough people enjoy listening to. Predicting the future isn't really the value-add for these sorts of shows.
The curse of knowledge
I think it's significant that by far the worst team in the contest is the Ringer NFL Show, which is primarily not about gambling. It's a show by extreme football nerds, for extreme football nerds. Once in a while I listen to it while doing the dishes, and I'll go like 20 minutes without recognizing a single player or football term they're talking about. They are all walking football encyclopedias, as far as I'm concerned.
If gambling really were a matter of football-knowing, they should be winning. They aren't, because betting isn't a football-knowing contest.
I can see how being a true expert might make somebody worse at gambling. Every bet is a math problem, not a trivia question. A bet at a -4.5 spread might have a positive expected value, but a -5.5 spread have a negative expected value. People who are good at sports gambling can somehow tell the difference. Like life, sports gambling is a game of inches.
The folks on the Ringer NFL Show know the name of the backup Left Tackle for every team in the league, but I don't think that's really an advantage in knowing whether -4.5 or -5.5 is the right number for a particular game. Most of the cool football stuff they know should already be baked into the line, or is irrelevant. Sports betting is a lot more like The Price Is Right than it is like sports.
A great chef might know practically everything there is to know about food. They might know what type of cheese is the tastiest, how to cook with it, and so on. But if they went to the grocery store, that doesn't mean they would notice that they had gotten charged the wrong price for the cheese, or that they could get it 20% cheaper at another store. That's a totally different skillset and mindset.
People on these gambling shows spend several minutes explaining each of their picks, listing lots of seemingly good reasons. I think that having to give a good reason for each pick forces them into going with what they know, not considering that all the obvious information and most of the non-obvious information they have is already reflected in the line. Needing to be seen as an expert could lead them to pick the side with slightly less value on it, because they want to make a defensible pick. It's much better to have a good sounding reason for making a pick, and losing, than it is to have no reason for making a pick and winning.
In general, I think every bet has a more reasonable side and a crazier side. Anybody prognosticating for a living has a disincentive to pick the crazier side if they're going to have to explain the bet if they happen to lose. It doesn't if there was actually more value than the Browns. Losing on the Browns and then having to live with being the guy who bet on the Browns is two losses at once.
The Mathletix Bajillion, week 10
I figured I should take a crack at it. The season is mostly over, so it will be a small sample size, but let's see what happens. At the very least, it will force me to publish something at least once a week for the next couple of months, and if things go bad, work on developing the shamelessnesss of someone who gets paid to predict the future, even though they can't.
I'm going to make two sets of picks, one based on a proprietary betting model I created, the other purely random, based on rolling dice. At the end, I will reveal which team is which, and see how they do against the Ringer's teams.
I am an extremely casual fan of the NFL, so little to no actual ball-knowing will go into these picks. I probably know less about football than the average person who bets on football. I don't think that's really a disadvantage when the football experts are going 18-27 on the year.
I will take all bets at -110 odds or better. No cheeky -120 bets to goose the win-loss record a bit, like some of the teams in the Ringer competition have done. But I will also shop around between sportsbooks and take the best lines I can find, by checking sites like unabated, reduced juice sportsbooks like lowvig and pinnacle, and betting exchanges like matchbook and prophetx.
For the betting exchanges, I will only take spreads where there is at least $1000 in liquidity -- no sniping weird lines. Part of what I'm trying to show is that bargain shopping, which has nothing to do with football knowledge, can make a big difference. So I will shop pretty aggressively. Even if I lose, I will lose less fake money than I would at -110, which means I don't have to win as often to be profitable. I'm pretty confident I can beat the Ringer pros on that point at least.
Sources will be noted below.
Team names come from the 1995 crime drama Heat, starring Tom Sizemore, in accordance with the Ringer house style.
Picks were made Friday evening.
The Neil McAul-Stars
- ATL +6.5 -108 (fanduel)
- NO +5.5 -109 (prophetx)
- SEA -6.5 -110 (prophetx)
- PHI +2 -109 (Rivers)
- LAC -3 +104 (prophetx)
The Vincent Hand-eggs
- DET -7.5 -105 (prophetx)
- PIT +3 -109 (prophetx)
- TB -2.5 -110 (fanduel)
- CHI -4.5 -105 (fanduel)
- CAR -5 -110 (harp rock casino)
Nov 14, 2025
Song: Scientist, "Plague of Zombies"
This is a departure from the usual content on here, in that there's no real math or analysis. There's also not much of an audience for this website yet, so I hope you'll indulge me this week.
I was curious what all these gambling shows talk about for hours, when the picks they produce collectively appear to be no better than randomly chosen. I'm always interested in how people make decisions. How does their process work for choosing what bets to take? How might it work better?
Before I get too far into this, I know I'm being a killjoy. These podcasts are for entertainment purposes, just like betting is entertainment for a lot of people, not a sincere attempt to make money over the long term. Some degenerate gambling behavior is part of the appeal of these podcasts. They're selling the idea that "gambling is fun" as much as any particular bets.
It's still weird to be a gambling expert who can't do better than a coin flip.
I previously showed how combining multiple machine learning algorithms thru voting will only improve results when they make independent mistakes, and are significantly better than guessing. Those are both pretty intuitive conditions, and I think they're true of groups of people as well. If everybody has the same opinion, or makes the same sort of mistakes, or nobody really knows anything, there can't be a wisdom of crowds.
Humans have a big advantage over combining machine learning algorithms. We can talk with each other, challenge each others' assumptions, provide counterexamples, and so on.
There's not a ton of that in the gambling podcasts I listened to. Gambling talk is all about inventing stories about the future. It's sort of a competition for who can pitch the best narrative for the game. These stories are almost their own literary genre, and the construction of these are more important than the picks themselves. There aren't a lot of opportunities for the wisdom of crowds or some sort of error correction to occur.
Imagine I had a magic black box that was right about NBA lines 56% of the time. I could sell those picks, and be one of the better handicappers on the internet. While I could certainly write a little story for each one, maybe in the style of Raymond Carver -- "Will You Please Take The Over, Please?" -- the story doesn't make the bet more likely to be true, though, right? A factual story would be the same for every bet, and not very interesting: "there is slightly more value on this side of the bet, according to the model."
What we talk about when we talk about sports betting
Gambling personalities are always talking about what has happened in the past -- connections to previous games they've bet on, dubious historical trends, and the tendencies of certain players. Interactions like, "I thought you had a rule never to bet against Baker Mayfield?" "But he's 2-7 on the road in early Sunday games after a Monday night game where he got over 30 rushing yards."
These arbitrary connections remind me of a bit from Calvino's Invisible Cities:
In Ersilia, to establish the relationships that sustain the city's life, the inhabitants stretch strings from the corners of the houses, white or black or gray or black-and-white according to whether they mark a relationship of blood, of trade, authority, agency. When the strings become so numerous that you can no longer pass among them, the inhabitants leave: the houses are dismantled; only the strings and their supports remain.
There were quite a few of those useless strings in the November 6th episode of the Ringer Gambling Show.
The top bun
On a couple of occasions, the show discussed whether certain information was already priced into the line or not. Since gambling should be about determining which bets have positive expected value, that's a very useful thing to discuss. "If this spread looks wrong, what does the market know that we don't? Or what do we know that the market doesn't?"
If the goal is to win, the implicit question should always be: why do we think we have an advantage over other gamblers taking the other side? Why are we special? Why do we think the line isn't perfect?
Superstitions and biases
They were resistant to bet on teams that they had recently lost money on -- not wanting to get burned again. This is clearly not a financial choice, but an emotional one. The axe forgets, the tree remembers.
Team loyalty also affected their betting decisions. They avoided taking Baltimore because Ariel is a Ravens fan (the bet would have won). Jon suggested betting against his team, the Dolphins, which Ariel jokingly called "an emotional hedge". The Dolphins won. So they cost themselves two potential wins due to their fandom.
They decided not to take a bet on Houston (which ended up winning) because, in Jon's words, "betting on Davis Mills is not a pleasant experience". Whether a team or player was fun to bet on came up a couple of other times as well. Someone just trying to make a profit wouldn't care how fun the games are to watch. They might not even watch the games at all. Whether the gambler watches the game or not has no influence on the outcome.
Bets need to be fun, not just a good value. These gambling experts still want to experience "the sweat" -- watching the game and rooting for their bet to win. As I wrote last week, betting on the Browns and losing is like losing twice, so even if the Browns are a better value, they are a bad pick for emotional reasons. Who wants to have to be a Browns fan, if only for a few hours?
It's sort of like Levi-Strauss said about food. It's not enough that a type of food is good to eat, it must also be good to think about. The Houston Texans led by Davis Mills are not "bon à penser".
Not enough useful disagreement
All three of the bets they were in total agreement on (PIT, TB, ARI) lost. Nobody presented a case against those bets, so there was no opportunity for any of them to change their minds or reconsider their beliefs.
I'm not endorsing pointless contrarianism -- not every side needs to be argued. Don't be that one guy in every intro to philosophy class. But if both sides of an issue (or a bet) have roughly equal chances of being true, there should be a compelling case to be made for either side. Someone who can't make both cases fairly convincingly probably doesn't know enough to say which case is stronger.
Two types of hot streaks
For gamblers, there's one type of hot streak that's always bound to end. A team has won a few games it shouldn't have won, therefore they're bound to lose the next one. Their lucky streak will fail. In the real world, there's no invisible hand that pulls things down to their averages on a set schedule. In a small sample size of 17 games in an NFL season, there's no reason to think things will be fair by the end, much less the very next game. Now, a team could be overvalued by the market because they got some lucky wins, which makes them a value to bet against. But teams don't have some fixed number of "lucky games" every year, and once they've burned through those, their luck has to turn.
The other type of hot streak is bound to keep going. The team were divided whether to bet the Rams or not. They decided to go with Ariel's opinion, because she's been on a hot streak lately. If Ariel's record was demonstrably better than the other two hosts' over a long period of time, it would make sense deferring to her as the tiebreaker. But winning a few bets in a row doesn't mean the next bet is any more likely (or less likely) to win. As a teammate, that's a supportive thing to do, so I'm sure that's part of it. But people who gamble tend to think they have it sometimes, and don't have it other times. Sometimes they're hot, sometimes they're cold.
We've seen this before with NBA basketball. Basketball players have an innate tendency to believe in the hot hand, even though it doesn't exist, so much so that it actually hurts their performance.
Why would the hot hand exist when it comes to predicting the future? What laws of physics would allow someone to predict the future better at some times rather than others? A gambler, regardless of skill level, will occasionally have hot streaks or cold streaks based on chance alone. So a gambler on a hot streak shouldn't change what type of bets they take, or how much they wager, just like NBA players shouldn't change what type of shots they take. But they do.
The problem with props
They suggested a bunch of prop bets. 5 of the 6 suggested were overs -- bets on players scoring at least one touchdown, or going over a certain number of yards. 4 out of 5 of the overs lost.
Gamblers greatly prefer betting the over on prop bets, which creates a problem. There's little to no money wagered on the under, which means gamblers taking the over are betting against the house, not other gamblers. That should be a warning sign. Sportsbooks are rational economic engines. If they're taking on more risk in the form of one-sided bets, they're going to want more reward in the form of a higher profit margin.
For a lot of prop bets, the big sportsbooks don't even allow taking the under. If a gambler can bet both sides, at least we can calculate the overround, or profit margin on the bet. With one-sided bets like these, there's no way to know how juiced the lines are (my guess would be to Buster Bluth levels.)
Traditionally, a sportsbook wants to have equal action on both sides of a bet. They don't really care what the line is. As long as the money's basically even (they have made a book), they can expect to make money no matter which team comes out on top.
With these one sided prop bets, there's no way for the free market to move the price by people betting the under instead. So the line doesn't need to be that close to the actual odds. Without action on both sides, sportsbooks have to be extremely vigilant about never setting an inaccurate line that gives the over too much of a chance of winning. And I don't think that gamblers taking overs on prop bets are too price sensitive. So the sportsbooks have multiple reasons to make the overs a bad deal.
Even sportsbooks that offer unders charge a huge amount of vig on prop bets to offset the additional uncertainty to the sportsbook. There are so many prop bets on each game relative to the number of people who take them. They can get away with setting the lines algorithmically because the lines don't need to be all that accurate with a bunch of extra juice on top.
This screenshot is from an offshore "reduced juice" sportsboook that allows bets on the unders.
We can convert the lines to win probabilities and add them up to calculate the overround, as covered a couple of articles ago.
For the Saquon Barkley bet, the overround is 8.9%. For Hurts it's 8.3%, for Brown it's 7.4%, and 7.9% for Smith.
The overround for a normal spread bet is 4.5%. We saw it's about the same with NBA money lines. Because this book is reduced juice, overrounds on spread bets are around 2.6% -- for instance odds of -108/-102 or -105/-105 instead of -110/-110.
Prop bets have 2x the juice of a traditional spread bet, and over 3x reduced juice. That requires the gambler to win far more often just to break even.
Ways to potentially reduce bias
I've previously written about an experiment that showed gamblers tend to take the favorite, even when they've been told it's a worse bet than the underdog. That wasn't true of the Ringer teams last week. They only took 11 favorites out of 25, so they didn't show that particular bias. But I think the experiment gives a hint how to reduce bias in general.
The researchers found that people could be corrected of their bias towards favorites by writing out what they thought the lines should be before seeing what the lines were. It causes the person to actually try and do the math problem of whether the bet is a good investment or not, rather than anchoring on the price set by the market, and picking the better team, or the conventional wisdom.
It would be interesting to try having each team member decide what the fair line was, then average them out. Do predictions made that way perform better?
Similarly, it would be helpful to convert any odds from the American style (like +310, or -160) to the equivalent probability. People who have gambled a lot might have an intuitive sense of what -160 means, but for me, the equivalent 61.5%, or "about 5/8" is much clearer. I can imagine a large pizza missing 3 of the 8 slices.
Betting jargon and betting superstitions should be avoided. Does each bet make sense as a financial transaction? Personal feelings and the enjoyability of the bet shouldn't factor in. The quality of the game and who is playing in it shouldn't matter.
The bottom bun
Despite not being a gambler, the gambling podcasts I listened to were fairly enjoyable. It's basically Buddies Talk About Sports, which is a pleasant enough thing to have on in the background. Nobody would listen to Casey's Rational Betting Show, for multiple reasons.
The Mathletix Bajillion, week 2
The Ringer crew had a good week, collectively going 14-11 (56%). One team out of five is now in the green. mathletix still won the week, winning 60% of our bets.
As a reminder, one set of picks is generated algorithmically, the other randomly. I'll reveal which one at the end of the competition.
"line shopping" refers to how much money was saved, or extra money was gained, by taking the best odds available instead of betting at a retail sportsbook.
All lines as of Friday morning.
The Neil McAul-Stars
last week: 5-0, +504
line shopping: +4
- LAC -3 +100 (prophetX)
- TB +5.5 +100 (lowvig)
- MIN -3 +105 (lowvig)
- ARI +3 -101 (prophetX)
- SEA +3.5 -111 (prophetX)
The Vincent Hand-eggs
last week: 1-4, -334
line shopping: +6
- LAR -3 -110 (hard rock)
- SF -3 -101 (prophetX)
- DET +2.5 +100 (lowvig)
- TEN +6 -107 (prophetX)
- GB -7 -105 (prophetX)
