QB trajectories

nflverse play-by-play, regular season, 1999 to date, scored play by play with the Margin QB Grade: the same per-game numbers as the quarterback board and every other QB page. A game gets a point on the chart when the quarterback had 10 or more dropbacks, and a QB is included once he has 16 such games. Plays from shorter appearances still count toward the running grade.

The running grade after each game adds up his points above an average play over his games so far, with a 32-game half-life so recent games count more, and pulls the total toward 50 by the equivalent of 218 average plays (about 200 dropbacks). Nothing from later games goes into it. We checked other half-lives (16 to 64 games) and the gap in how well the grade matched the next 16 games was small, so we kept 32.

The 80% band is checked, not assumed. A plain noise model covered only about 65% of quarterbacks' grades over their next 16 games, because players change over time, so the band is widened about 1.9 times to cover 80% across 10,643 checks. Fitting that widening on 1999-2012 alone and applying it to 2013 onward covered 77%, so the band is a little narrow for recent seasons. The league band is the 10th to 90th percentile of every QB's running grade at the same career game, for careers that began in 2000 or later. It rises late in careers because the weaker quarterbacks are gone by then.

The Margin Grade was chosen in a blind three-way study (Oct 2026): over ten out-of-sample seasons it tracked how many points an offense scored better than raw EPA per dropback and better than our earlier Skill and Form numbers. It describes how a quarterback played; it does not predict next season better than EPA per dropback does. None of this separates a quarterback from his line, receivers and play-caller. Seasons before 1999 are not in the data, so Peyton Manning's rookie year is missing.

Season grades, with more context per player, are on the quarterback board.