Game quality

What each result was worth beyond the score. Every play is graded by EPA (expected points added), then adjusted for who it came against: a defence's rating is what it allowed to everyone else that season, so a big day against a bad defence counts for less. Season views include playoff games.

Bailey Zappe — 2023

Adj EPA / dropback
-0.332
Raw EPA / dropback
-0.348
Dropbacks
236
Turnover EPA
-45.1
WPA
-2.05
WeekOpp DropbacksAdj EPA/dbRaw EPA/dbScheduleTotal adj EPA INT / FLTurnover EPASacksSack EPAWPACPOE
4DAL 10 -0.281 -0.300 +0.019 -2.8 0 / 0 +0.0 1 -1.5 +0.00 -12.9
5NO 9 -0.806 -0.841 +0.035 -7.3 0 / 0 +0.0 0 +0.0 +0.00 -24.6
10IND 7 -0.132 -0.118 -0.014 -0.9 1 / 0 -0.7 0 +0.0 -0.21 -16.6
12NYG 15 -0.441 -0.428 -0.013 -6.6 1 / 0 -5.0 1 -1.3 -0.22 -14.3
13LAC 30 -0.546 -0.524 -0.022 -16.4 0 / 0 +0.0 5 -11.2 -0.62 -11.2
14PIT 30 +0.035 +0.043 -0.008 +1.1 1 / 0 -7.1 2 -3.1 +0.01 +4.4
15KC 35 -0.318 -0.369 +0.051 -11.1 1 / 0 -6.4 4 -5.7 -0.03 +1.5
16DEN 34 +0.066 +0.086 -0.020 +2.3 0 / 1 -6.5 2 -8.0 +0.50 +13.4
17BUF 29 -0.388 -0.417 +0.028 -11.3 3 / 0 -17.7 3 -4.8 -0.53 +1.8
18NYJ 37 -0.684 -0.750 +0.066 -25.3 2 / 0 -1.7 7 -12.0 -0.97 -21.4
Opponent adjustment. A unit's rating for a game is its average over its other games that season, blended with 16 games' worth of prior (league average plus half of last season's gap from it; 24 games for pass defence, which is noisier). Early in a season that leans on last year; by midseason it is mostly this year. Chosen by how well it predicts a held-out game: it cut that error by about a quarter against no shrinkage, and adjusted numbers agree between odd and even weeks more than raw ones do (team EPA margin r 0.52 → 0.55, defence 0.32 → 0.36, QB EPA/dropback 0.47 → 0.49, 2016–2025).
Win expectancy is a logistic fit of wins on EPA margin over 6,036 completed games (it names the winner 86.5% of the time). These describe what happened; one game is not a forecast. Play-by-play credits the quarterback with every sack and dropback, so a bad line shows up in his numbers. Seasons 2016–2026, built 2026-09-14 01:25 UTC, from nflverse. Write-up: backtests/nfl_game_quality/FINDINGS.md.