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Using Sabermetrics to Project 2017 NFL Team Wins

Earlier this offseason I looked at which teams got lucky in 2016 from a sabermetrics perspective regarding won-loss record. Using each team’s Pythagorean win percentage, we can use their 2017 schedules to give an estimate of wins for each team in 2017.

Calculating Expected Team Wins

Pythagorean wins can be estimated using each team’s Pythagorean win percentage from the year prior. This is done via the Log5 formula. The formula states that if Team A has a Pythagorean win percentage of P­and Team B of P­B, then the probability of Team A winning (denoted W­A) is as follows:

W­A = (P­A – P­A * P­B) / [P­A+P­B – (2 * P­A * P­B)]

These win percentages are how the team would play at a neutral site. I’ve made adjustments so that if a team is at home, their Pythagorean win percentage is increased slightly while the visiting team’s Pythagorean win percentage is reduced slightly. The exact amount of these adjustments is such that it gives the home team an extra 2.7 point boost. From there, we can calculate the expected wins for each team over the course of the 2017 season.

It should be noted that it’s obvious that this is strictly a formulaic approach to calculating wins. The formula knows nothing of player development, personnel changes, scheme changes, or coaching changes that might influence the true win percentage of a team. However, since NFL wins are a net-zero sum (there have to be 256 wins every year1), then in the long run, these are true averages that we expect from each team, should the offseason with all the changes be randomized many, many times over.

To find Pythagorean Win percentages from 2016, check out this link. Let’s dive into the 2017 projected team wins.

2017 Pythagorean Team Wins

Team2017.Proj.W2017.Proj.L2016.WDiff2017.SOS
NE13.162.8414-0.840.493
ATL10.985.0211-0.020.507
DAL10.785.2213-2.220.535
SEA10.475.5310.5-0.030.461
PIT10.415.5911-0.590.472
ARI10.355.657.52.850.448
KC9.686.3212-2.320.551
IND9.416.5981.410.44
MIN9.336.6781.330.455
BAL9.336.6781.330.454
GB9.236.7710-0.770.499
TEN9.16.990.10.438
PHI8.97.171.90.509
CIN8.777.236.52.270.469
NO8.527.4871.520.495
NYG8.377.6311-2.630.527
DEN8.277.739-0.730.553
BUF7.998.0170.990.534
OAK7.938.0712-4.070.562
WSH7.758.258.5-0.750.546
DET7.568.449-1.440.494
LAC7.148.8652.140.532
CAR7.098.9161.090.508
TB7.048.969-1.960.525
MIA6.879.1310-3.130.54
HOU6.699.319-2.310.486
JAX6.69.433.60.445
CHI4.4411.5631.440.505
SF4.0311.9722.030.482
NYJ3.7512.255-1.250.541
CLE3.0912.9112.090.489
LAR2.9813.024-1.020.506

A few things stand out from the table.

  1. The Oakland Raiders project for approximately four wins fewer than they had last year. That’s because they get a bit of a double whammy. First, Oakland was the luckiest team in 2016 in terms of Pythagorean wins, with 3.05 wins more than their point differential suggested. They had a 6.67 average point margin in their wins, but their losses were by 7, 8, 16, and 18 points. In other words, every loss was more than their average win. They won several close games but lost by large margins. Second, Oakland faces the toughest schedule in 2017 based on their 2017 opponents’ Pythagorean win percentage from 2016. Expect some downward regression from a team that scored the seventh-most points in 2016.
  2. The Los Angeles Rams finished 2016 with a 4-12 record — the opposite of the Raiders — yet the Pythagorean wins method also expects them to perform worse. That’s because the Rams were 1.33 wins over expectation in 2016. Simply put, they were a 2.67 win team in 2016 based on their points scored and allowed. They also didn’t even finish in the cellar in the NFC West, with San Francisco taking those honors with a 2-14 record. That gives the Rams a slightly harder than average schedule, since they don’t get to face the cellar dwellers in the NFC. This is continued bad news for Todd Gurley, who only scored 124.5 fantasy points on the ground in 2016 compared to new Eagle LeGarrette Blount, who posted 108 fantasy points just from touchdowns in 2016. That’s the ultimate point in support of the hypothesis that game script matters for RBs more than RBs matter for game script.
  3. Despite the ninth-toughest schedule per Pythagorean wins, the Los Angeles Chargers project to win two games more than they did last year. That’s because the Chargers had some incredibly close losses, with a few of those coming after blowing big leads. The Chargers were closer to an 8-8 team last year with 410 points scored and 423 allowed. The schedule certainly hurts their playoff prospects, but they actually have the easiest 2017 schedule among all the AFC West teams. Expect Keenan Allen to play a big role in an offense that scored the ninth-most points in 2016.
  4. Jacksonville and Arizona project to improve by the most wins in 2017. Both of these teams were bottom three in wins over expectation2 in 2016 per Pythagorean expectation, and both of these teams have top-four schedules in 2017. That’s great news for David Johnson, who should continue to have plenty of red-zone opportunities. It also spells good things for Blake Bortles and Leonard Fournette, as the Jaguars figure to be in contention later into the game in more games in 2017 than they were in 2016.

What else strikes you as interesting from the Pythagorean win projections from 2017? Let me know in the comments below.

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  1. Counting ties as half a win for each team.  (back)
  2. In other words, they actually were tops in wins under expectation.  (back)
By RotoDoc | @RotoDoc | Archive

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