Game quality
How well each team played, beyond the score: EPA (expected points added) per play, adjusted for the opponent. A big day against a bad defence counts for less. Season views include playoff games.
PJ Walker — 2021 Every split →
Adj EPA / dropback
-0.199
Raw EPA / dropback
-0.200
Dropbacks
73
Turnover EPA
-9.3
WPA
-0.01
| Week | Opp | Dropbacks | Adj EPA/db | Raw EPA/db | Schedule | Total adj EPA | INT / FL | Turnover EPA | Sacks | Sack EPA | WPA | CPOE |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 7 | NYG | 17 | -0.800 | -0.782 | -0.018 | -13.6 | 0 / 0 | +0.0 | 3 | -5.7 | -0.06 | -39.0 |
| 8 | ATL | 1 | -0.327 | -0.258 | -0.069 | -0.3 | 0 / 0 | +0.0 | 0 | +0.0 | -0.01 | -62.4 |
| 10 | ARI | 29 | +0.208 | +0.183 | +0.025 | +6.0 | 1 / 0 | -3.2 | 0 | +0.0 | +0.07 | +3.9 |
| 12 | MIA | 14 | -0.336 | -0.381 | +0.045 | -4.7 | 1 / 0 | -3.9 | 4 | -4.8 | -0.01 | +0.1 |
| 14 | ATL | 12 | -0.162 | -0.083 | -0.079 | -1.9 | 1 / 0 | -2.2 | 0 | +0.0 | -0.00 | -8.4 |
How the ratings are built
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 2026-11-07 11:05 UTC, from nflverse. Write-up:
backtests/nfl_game_quality/FINDINGS.md.