Thursday, Sep 5th
Monday, Sep 9th

Vegas Odds

This course focuses on deep analysis of a single game, primarily for prop betting purposes. Showdown DFS players will also get great value out of this, as I’m going to dive into how to pick apart one game and identify what is most likely to happen in the game and which players benefit from that, as well as other plausible-but-less-likely scenarios. I’m going to talk a lot about data in here, and at the end I’ll put a brief appendix that shows all of the sources that I use to gather this data. There is a lot of premium data available in the NFL world, but for the most part you can get what you need for free from the sources I’ll link (though I’ll put in a brief plug for Pro Football Focus, or PFF, which has an elite package that is absolutely worth the money if you’re a serious bettor or DFS player). 

Vegas odds

The first thing I do when examining a game is to look toward Vegas. What’s the over/under of the game, what team is favored, and by how much? What is important to understand here is what an over/under line actually means. Intuitively, we would think the line represents Vegas’ guess of the most likely outcome for total points scored in the game, with a roughly normal distribution tailing off to either side. But, that isn’t necessarily correct. The motivation for bookmakers when making lines isn’t to find the average of the points scored if the game were to be played 100 times; it’s to get an even amount of money bet on the over and the under, which guarantees them a profit on that game. Because bettors are human, popular teams tend to attract more bettor interest, and “big” games between two good offenses tend to attract a lot of bets. Plus, for most fans, it’s more fun to bet on “over” outcomes, both for games and for individual player props. It’s more fun to root “for” something than “against” something. 

While I don’t bet lines themselves, we can use this information to try and figure out what the game environment is likely to be. Obviously, a high total game is expected to be a shootout, while a lower-total game is more likely to be either a slow-paced slugfest or a sloppy game full of turnovers and little scoring. The more nuanced view, though, is that game scoring doesn’t have to be a normal distribution. It could be a barbell, for example: reasonable probabilities of both a high-scoring game or a low-scoring game, with a scoring outcome right around the line actually being a less likely outcome. This can happen with teams with unreliable but explosive offenses (in 2019, some good examples would be the Bills and the Cardinals). 

Where this is most relevant for prop betting is that player props generally have lines built around a player’s average outcomes. If Adam Thielen has averaged 6 catches per game, the even money line will probably at over 6.5 catches. Then, those lines are modestly adjusted for the matchup and Vegas odds. A high total game will result in a bump up, a low total game gets a bump down. Having a more sophisticated understanding of what Vegas lines mean gives us an edge, because a high total game doesn’t necessarily mean a given player will exceed their normal expectations and a low total game doesn’t mean they will fall below their normal production.