Bill James brought the Pythagorean theorem to light many years ago as a way to indicate a baseball team’s future performance based on runs scored and allowed as it correlates to its winning percentage.
From there, a formula was created to apply to the NFL. While I am not sure who was responsible, I do know Football Outsiders has researched it as a way to predict a team’s record based on the prior year’s performance. While it’s only one piece of the puzzle, there are some definite lessons we can learn to help gauge NFL win totals for the upcoming season.
As an example, the Los Angeles Rams went 13-3 during the 2018 regular season and scored 527 points while allowing 384 points. The theorem suggests the Rams should have won 10.9 games and lost 5.1 games. So the Rams won 2.1 more games than they should have, based on this formula.
When looking at all teams since 2007 that won at least two more games than they should have, and at what that meant for the following season’s win totals, we can draw this conclusion: Go with the Under on those teams.
There have been 21 teams in that span that fit the criteria, and if you had bet the Under on their win totals, you would have gone 17-3-1. Of those 21 teams, 17 won three fewer games the following season, including all seven teams that won 13 or more games the prior season. This would suggest the Rams will win 10 or fewer games this season despite being tasked with a 10¹/₂ season-win number.
Let’s take this one step further. Teams that overachieved the theorem likely also had good fortune in close games. The more close games you win, the greater likelihood that fortune will regress to the mean the following season. The 2018 Rams not only won 2.1 games more than their numbers suggest they should have, they went 6-1 straight up in games decided by seven or fewer points during the regular season. The Rams had an extreme amount of good luck in close games. By my count, at least four of those six wins could have gone the other way.
When we go look at only those teams among the 21 that won at least four more close games than they lost, we find they went 13-1-1 Under their win total the following season.
What about the other side of the coin — teams that underachieved the previous season? Since 2007, there have been 25 teams winning at least two fewer games than their Pythagorean numbers suggest they should have won. We would expect them to go Over their win total the following season. Those 25 teams went 16-8-1 versus their season win total.
Last year, the New York Giants went 5-11 but their Pythagorean numbers suggested they should have won seven games. The Giants also were an unfortunate 4-8 in close games. They are being asked to win six games this year. That total is heavily juiced to the Under, meaning you can take plus money on Over six wins.
This system recommends the Rams Under 10¹/₂ wins, Cowboys Under 9 wins and Giants Over 6 wins. Let’s see how it turns out.
