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 runs allowed, as it correlates to its winning percentage.
From there a formula was created to apply it to the NFL as well. While I am not sure who created the NFL formula, I do know Football Outsiders has given it some research as a way to predict a team’s performance based on their prior year.
I’ve used this over the last twelve years or so to help gauge NFL season win totals for the upcoming season. While it’s only one piece of the puzzle, there are some definite lessons we can take from it to set us in the right direction. So let’s take a look at what we can learn from this geometry class formula from the tenth grade.
Green Bay Packers
Let us start by applying the Pythagorean Theorem to the 2019-20 NFL season. The Green Bay Packers went 13-3 during the regular season, scoring 376 points and allowing 313 points. The Pythagorean Theorem suggests the Packers should have only won 9.7 games and lost 6.3 games. In other words, the Packers won 3.3 more games than they should have based on this formula.
Pythagorean Theorem: Historic performance
So let’s expand on our use of the Pythagorean Theorem. Going back to 2007, let’s look at all teams that won two or more games than they should have and how that correlated to the next season in terms of their total wins performance.
If a team over-achieved in prior year by two or more games, then we’d look to go under their season win total the following season. Since 2007 there have been 22 such teams. Betting those teams’ under season win total the following season, you would have gone 18-3-1.
Of those 22 teams, 18 of them won three fewer games the following season – including all eight teams that won 13 or more games the previous season.
The New Orleans Saints also went 13-3 last year, but their numbers suggest they should have only gone 10.7 – 5.3 – meaning they overachieved by 2.3 wins. They also went 6-1 in games decided by seven or fewer points during the regular season.
Two other teams also overachieved by two or more wins last year: the Seattle Seahawks, going 11-5 (8.2 – 7.8), and the Houston Texans, going 10-6 (7.8 – 8.2).
So the Packers, Saints, Seahawks and Texans all overachieved by two or more wins last year.
The next step…
Let’s take this one step further.
Teams winning more games than their numbers suggests that they perhaps had very good fortune in close games.
And the more close games you win, the greater likelihood that fortune will regress to the mean the following season.
The 2019 Packers not only won 3.3 games more than their numbers suggest they should have, but they also went 6-1 in games decided by seven or fewer points. They had an extreme amount of good luck in those close games.
So let’s go back and look at those 22 teams that over achieved by a minimum of two games
Of those, 16 won four or more close games than they lost. And we find that those teams went under their season win total the following season to the tune of 14-1-1.
All four teams listed above won four or more games than they lost in close games last season. So the Packers, Saints, Seahawks and Texans all look to be unders plays this year based solely on this formula.
Just before we move on, let’s look at a 2018 team based on their 2017 numbers that qualified for this situation. The Pittsburgh Steelers went 13-3 in 2017, while their Pythagorean numbers suggested they should only have won 10.5 games or 2.5 fewer. The Steelers were also a very fortunate 8-2 in games decided by seven or fewer points in 2017.
In 2018, they slipped back to 9-6-1 (four less wins), while going a more normal 6-5 in close games. And, true to form, they went under their season win total of 10 wins.
Last year the Rams applied to this same formula that we outlined in these pages. They came through by only winning nine games and going under their 10.5 season win total despite being in the SuperBowl the season prior.
The other side…
What about the other side of the Pythagorean Theorem coin – teams who under achieved the previous season?
Since 2007 there have been 26 teams that won at least two games less than their Pythagorean numbers suggest they should have won. We would look to go over their season win total the following season.
Those 26 teams went 16-9-1 the following season versus their season win total. We have four underachievers from last season that qualify this year:
- The Detroit Lions went 3-12-1 last year (Matthew Stafford was injured), but should have gone 6-10 based on their numbers.
- The Dallas Cowboys went 8-8 last year, but should have gone 10.7 – 5.3 based on their numbers.
- The LA Chargers went just 5-11 last year, but should have gone 7.8 – 8.2 based on their numbers.
- The Cincinnati Bengals went just 2-14, but should have gone 4.4 – 11.6 based on their numbers.
So there’s four teams that fit the Pythagorean Theorem billing this year.
Let’s look at a 2017 number that fit that mold for the 2018 season. In 2017 the Cleveland Browns went 0-16 but their Pythagorean numbers suggests they should have won 3.3 games in 2017. Despite being marked with a six-win total for 2018 (six more games than they won the prior season) the Browns still managed to win seven games and go over their season win total number.
A side note to this is teams that won 8 or more games and still under achieved by at least two wins the previous season have gone over their season win total the following year all five times since 2007. The Dallas Cowboys fit that formula this year having gone 8-8 last year, but should have gone 10.7 – 5.3. In other words, they underachieved by 2.7 wins but still won eight games in 2019.
Between the two situations suggesting to either go over or under a team win total, since 2007 following these Pythagorean plays you would have gone 34-12-2. This year there are eight plays that apply. The three best are listed below.
Overachieving 2019 teams to fade in 2020
Green Bay Packers: Under 8.5 or 9 wins
As mentioned above, the Packers were incredibly lucky last year going 6-1 in games decided by seven or less points. Green Bay also lost Bryan Bulaga to free agency, as well as Blake Martinez. Detroit figures to be tougher with a healthy Matthew Stafford all year, and the schedule will not do them any favors either. Their own division had three teams at .500 or better. They face the other #1 teams from the NFC in San Francisco, New Orleans and Philadelphia, plus they face an AFC South Division that has three teams all capable of finishing .500 or better. And they will face the improved Tampa Bay as well.
New Orleans Saints: Under 10.5 wins
The Saints have won their division three straight years, including winning 13 games each of the last two years. But last year they only won three games against teams who finished the season above .500. This year their schedule sees them play all but two games (Carolina) against teams with season win totals of seven or higher. Add in they went 6-1 in games decided by seven or fewer points in the regular season, and they will need to again be incredibly fortunate in close games to get over their season win total. Tampa Bay figures to be much tougher this year with the addition of Brady and Gronkowski. The Saints will also face first place teams San Francisso, Green Bay and Philadelphia, in addition to defending SuperBowl champs the Kansas City Chiefs.
Underachieving 2019 team to play in 2020
Dallas Cowboys: Over 9.5 or 10 games
Mike McCarthy takes over from Jason Garrett as head coach for Dallas. McCarthy faced plenty of criticism at the end of his run in Green Bay. But he’s always been a particularly good quarterback coach. And he used his one year in hiatus to retool his offensive scheme. The Cowboys managed to win eight games last year despite going 0-5 in games decided by seven points or less. They play five games against teams predicted to win less than seven games (Cincinnati, Giants and Washington). They were just 2-7 in games against teams finishing .500 or above last year. That includes being 0-4 in games decided by seven or less points. Those close losses have a way to even themselves out from year to year. If they do that the Cowboys have a chance to go over their season win total.
How it works
Keen to know how the Pythagorean Theorem is applied to the NFL? Start here for an explanation.
So here’s is a toast to that 10th grade geometry lesson that we should have paid more attention to! Hopefully it puts a few bucks in our pockets this year.