Trends are bullshit
Almost all the "trends" you see in sports betting media are nothing more than fodder to make someone sound smarter
Trends are the ultimate tool for defending picks. There’s only one problem: they often don’t mean anything. Throwing a complicated trend in someone’s face may make you sound smarter — it’s clear you’ve done some research — but it doesn’t tell you about the game you’re betting on.
I saw a trend last week on twitter that drove me up the wall. I don’t have the tweet handy but it went something like this: “Teams who lose two games in a row as -135 favorites or more are 18-1 as underdogs dating back to 2013. Minnesota is in that spot today”. Let’s analyze this.
This trend is full of bias enhancers. It attacks your brain in ways that make you feel invincible. Immediately the first thing that stands out is 18-1. That’s a crazy record. It’s flashy, it gets your attention. The next thing is “dating back to 2013”. That shows this trend isn’t a recent fluke. It’s been going on for a long time. The third thing is the complicated nature of the situation, which leads you to construct your own narrative. The better team (-135 favorites) has lost back-to-back games —> they’ll be extra motivated and there’s no way they lose three in a row! There’s only one massive problem: This trend has nothing to do with the actual game.
There is nothing predictive about past record and line history. Not one thing. This trend makes no mention of the characteristics of the teams playing in the upcoming game or the teams involved in these games in the past. Also, a 19-game sample size over the course of 9 years is miniscule. That’s only 2.11 times per year. Lastly, a 19-game sample is super random… that’s because the 20th time doesn’t support the narrative. 18-1 sounds a lot better than 18-2 or 19-3.
It is, for lack of a better term, bullshit.
So how do we, as bettors and media consumers, sift through the bullshit and separate the legitimate trends from the fodder? Think of sports like weather.
If a weatherman told you there was a 25% chance of rain because it rained 1 of the last 4 Mondays, you’d think he was the worst weatherman of all time. You’d say screw the last few Mondays, look at the damn radar! On the other side of the equation is the best weatherman, who looks at the radar first and then brings the past into it. He identifies the type of cloud (cumulonimbus), the temperature (75° F), and the humidity (68%), THEN says “in the past 10 years, when cumulonimbus clouds of this size form with 75 degree temperatures and 68% humidity, it has rained 90% of the time. Expect thunderstorms tomorrow.” That’s how you motherfucking forecast.
So when it comes to sports, think like the good weatherman.
The first thing to look for is anything relating to the conditions of the upcoming match. This could be a set of statistics that applies to both teams (1) or something to do with the weather or stadium (2). Here are simple examples of both of those:
Team X has a 30% strikeout rate vs. LHP
The wind is blowing north-to-south at 19 mph
Both of these are tangible and quantifiable characteristics of the upcoming game. They do not guarantee any outcome, but they identify something that applies to the game you’ll be betting on.
The next thing to look for is a large sample size with the same characteristics.
Since 2005, there are 472 instances of a team is striking out 30% of the time or more vs. the handedness of the opposing starting pitcher…
Since weather started to be kept as an official stat in 1988, games with goalpost-to-goalpost winds of 19 mph or more…
The final thing to look for is a success rate greater than the implied probability of the odds you’re getting. Raw win rate means nothing without the context of the available odds. You might see a real trend with a 75% win rate, but the selection is -350 which is a 77.8% implied probability. So you may win at 75% betting these spots, but you’re getting paid 29 cents on the dollar as opposed to the 34 cents you’d need to break even.
These teams have a record of 178-293-1, or a 37.7% win rate (+165 break even point). Team X is +195 today.
In 1283 games with these wind conditions, the average longest field goal is 53 yards. The line for longest field goal is 47.5 (-110/-110).
Time to put it all together. If these were real they might actually be worth betting on:
Team X has a 30% strikeout rate vs. LHP. Since 2005, when a team is striking out 30% of the time or more vs. the handedness of the opposing starting pitcher, they have a record of 178-293-1, or a 37.7% win rate (+165 break even point). Team X is +195 today.
The wind is blowing north-to-south at 19 mph at Gillette Stadium today. Since weather started to be kept as an official stat in 1988, games with goalpost-to-goalpost winds of 19 mph or more have an average longest field goal of 53 yards. The line for longest field goal is 47.5 (-110/-110).
And there you have it. Two trends that actually mean something. Nothing to do with line history. Nothing to do with the day of the week or the time of the game (though this could have minor effects on certain things). The time horizons aren’t cherry-picked to make the trends look better than they actually are. And most importantly, they identify value spots compared to the expected prices/lines.
Now, here’s what separates the pros from the Joes… Strikeout rate splits are not the only thing to consider when betting on a game. Pitcher Y might be left handed, but maybe Team X is throwing their worst pitcher and their best hitter is injured. Maybe true price for Team X should be +235. The trend may mean something, but it certainly doesn’t mean everything.
Trends can be useful if they have the traits I outlined above. However, they are not the end-all-be-all, especially for individual games. Trends only work in very large samples and only if you bet all of them. If you pick your spots you’ll succumb to normal variance, feeling smart sometimes and like an absolute moron other times. But that’s all of sports betting, right?
OK time to wrap this up. The moral of the story is that most of the trends you see online are bullshit. When you’re watching Bear’s Board during College Gameday and he says something like “teams are 12-3 ATS when getting 8 or more points at home” you’ll finally understand that Bear is just a bad weatherman and a point spread has nothing to do with success rate. Nor does seeding in March Madness (the nuance here is that seed is indicative of the underlying traits of the team that could lead to a real trend, but the seeding itself means nothing). So next time you see a trend that focuses on price, seed, name, mascot, point spread, or what the team ate for dinner last weekend, you can feel sorry for the poor chap spewing nonsense who has convinced himself he found a way to beat sports betting. He’s just a bad weatherman who doesn’t know any better.
Lesson of the day
LEARN DECIMAL ODDS. If you go on a sports betting website in Europe you’re not gonna see -150, you’re gonna see 1.67. You’re not gonna see +135, you’re gonna see 2.35. Those are called decimal odds and every other country on earth uses them, like the metric system.
Decimal odds tell you what you’ll get paid on a winning $1 bet. If you multiply the stake by the decimal odds, you’ll get the payout. Quick, tell me what a $100 bet pays at -175 odds? You have no idea, do you? In fact, I wouldn’t even know how to attack that math problem. However, if you knew -175 was 1.57, you’d easily be able to say $100 at 1.57 pays $157. You’d win $57 on that bet.
The best part about decimal odds, though, is that it makes it impossibly easy to calculate the implied probability of your bet. All you need to do is divide 1 by the odds and you’ve got the probability.
1/1.57 = .636 which means 1.57 (-175) implies a 63.6% chance of the outcome happening. Way easier than the equations you need to know for American odds.
Content recommendations
The Logic of Sports Betting by Ed Miller and Matthew Davidow is a great introduction to a lot of sports betting theory. A lot of what I cover in this newsletter is covered in that book, and this book gave me a lot of the foundational knowledge to progress in the sports betting industry. Highly recommend this to anyone looking to become a smarter bettor.
That’s all folks
And that’s it! Thank you all so much for reading and you can always find me on twitter @Ben13Porter to chat about anything you’d like. Please feel free to subscribe to this newsletter if you haven’t already done so and to share it with anyone who might find it interesting!