Monday, December 12, 2011

Fun With NFC East Pythagenport Records

(Originally published, for better or worse, at Bleeding Green Nation)

Those who are familiar with baseball and The Good Phight are no doubt familiar with the concept known as Pythagorean records. In short, it is a formula invented by Bill James serving as a means of predicting a baseball team's record based off runs scored and runs allowed. A few years ago, a writer at Baseball Prospectus named Clay Davenport figured out that because the offensive environment of the league changes with time, the exponent used in the formula should be changed as well to reflect that. Hence the name in the title, Pythagenport records. And if one seeks to be even more accurate, one can derive an exponent for each individual team as each individual team plays in a slightly different offensive environment. While Baseball Prospectus calls this Pythagenpat records, in their Week 13 DVOA column from which this little exercise is derived from, Football Outsiders continue to use the term Pythagenport. For the sake of consistency, I will use the term "Pythagenport" throughout the rest of this column.

The same principles invented by Bill James can also be applied to NFL football. Now I know the question of how this is relevant will eventually come up, so I will answer it before we get into the numbers, so you understand right away what you are looking at. Football Outsiders did the math on this in the above linked column, and on a scale of 1 to -1 with 1 being the two variables are a perfect positive relationship on each other, 0 being the variables are completely independent of each other, and -1 being a perfect negative relationship, the correlation between Pythagenport wins and actual wins from 1990-2010, according to Football Outsiders, is .9134. This is a very strong correlation and the numbers that you are about to see below are relevant and will tell us about the 4-teams in the NFC East.

The formulas used in this column are as follows.

Exponent = 1.5*log ((Points scored + Points allowed) / number of games)
Pythagenport win percentage = Points scored^exponent / (Points scored^exponent + Points allowed^exponent)

As a baseline, here is each NFC East team's actual win percentage rounded to the nearest thousandth.

New York Giants: .538
Dallas Cowboys: .538
Philadelphia Eagles: .385
Washington Redskins: .308

And now each team's Pythagenport win percentage:

Dallas Cowboys: .575
Philadelphia Eagles: .511
New York Giants: .452
Washington Redskins: .284

What Does This Mean?

First of all, in case you have not yet figured it out, the NFC East is a bumbling pile of mediocrity plus the abysmal Washington Redskins. The best team in the division, the Dallas Cowboys, are somewhere between a 7-6 team and an 8-5 team when you convert the three-digit percentage number into actual wins.

Perhaps what may be startling to some but less so to folks who have been paying attention close attention to the Eagles' point differential, the 2011 Philadelphia Eagles are not all that bad of a football team. Certainly not as bad as their 5-8 record would lead you to believe. Now a record hovering around .500 is certainly not what many people, Eagles fans included expected out of the Eagles coming into the 2011 campaign, but it is certainly better than the Eagles' actual 5-8 record and enough to have the Eagles right in the middle of the NFC East title race without having to rely on some sort of miracle as they currently do.

So why is there a such a discrepancy between the Eagles' actual win percentage and Pythagenport win percentage?

A very good question, and the answer probably is not what people want to hear and/or believe, although it is true. In one word: luck. In two words: bad luck*.

*Addendum: In this context, I am attributing luck to the reasons why the Eagles are 5-8 and not hovering around .500. I am not suggesting luck is the reason the Eagles are not 10-3 or better and right in the midst of a race for a 1st round bye with San Francisco and New Orleans. This is also not to say the Eagles do not have flaws. Clearly, this is not a perfect team. However, they are not as bad as a 5-8 record (.385 win percentage) would suggest.

A basic theory of football is there is the ability to win close football games (with close football game being defined as games where the final margin of victory is 7 points or less) is not an actual ability. Some might define this perceived ability as being "clutch." But alas, no coach/QB/team hold an ability to consistently win/lose close football games. Over the course of a season, teams will tend to hover around the .500 league median. In his article last Friday, Bill Barnwell elaborates on this general point further with Tim Tebow's performance being the subject of the post. To go back to the Eagles, the Eagles are 2-5 this season in games where the final margin of victory is 7 points or less. The bad luck the Eagles have seen in these close games is a major reason why the Eagles' actual win percentage is as far below the Eagles' Pythagenport win percentage as it is. The fact that over 50% of the Eagles games have been decided by a touchdown or less is part of the reason their Pythagenport win percentage hovers around the .500 mark.


Barring a near miraculous final three weeks of the season, the narrative of the 2011 Philadelphia Eagles will be written as followed: "A team with all sorts of talent but no heart and a coach that lost the locker room. (Insert bad Dream Team pun here)." Unfortunately for many in the media, that narrative does not match with the reality. Barring a drastic turn of events in the final three games of the season, the 2011 Philadelphia Eagles were a team whose actual record fell well below that of what it should have been, according to Pythagenport win percentage, a metric whose that correlates very strongly (.9134) with actual win percentage. The Eagles Pythagenport win percentage (.511) is by no means great, however, in a watered down NFC East where mediocrity reigns supreme, is good enough to have the Eagles in line to contend for the division title. However, thanks to a couple unfortunate losses early in the season, the Eagles are only hanging on by a thread and would need everything to fall just perfectly into place in the final three weeks of the season to have a chance at winning an NFC East championship.


  1. Denver is 8-5 with a -33 point differential.

    Philadelphia is 5-8 with a +5 point differential.

    That's everything you need to know.

    The Eagles are an 8-8 or 7-9 team and will probably finish the season that way. Basically if they win out it will simply be how they're expected to finish.

    Of course the issue with Philly is not entirely bad luck as you said, but when you have an offense that turns it over so much as the Eagles, you will lose games you should've won. Well, except the Seahawks game, which we would've won anyway. ;)

  2. If they win their last three games by close margins it will probably end that way, but if they blow their final three opponents out, their Pythagenport record will naturally increase as well.

    I am not someone that despises Tim Tebow, but I can't wait for him and the Broncos to crash back down to earth, if only for the media coverage.


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