How a fourth-down decision is graded
Snap Theory grades a fourth-down call by win probability: for going for it, punting and kicking it estimates the chance of each result (convert or fail, make or miss, where a punt lands) and the win chance after each, and the option with the highest win chance is the best call. NFL rates come from nflverse play-by-play since 1999, each era graded with its own rates; college has its own models from 2014–2025 FBS play-by-play.
How accurate is it?
Checked against nfl4th (nflverse) on 3,200 NFL fourth downs from 2018–2025: the same best call on 75% of plays, and on 95% of the plays where both models say one option is clearly better (by 1.5+ points of win chance). The largest known difference is 4th and 3–6 inside the opponent’s 35, where Snap Theory leans toward going for it more than nfl4th; that is being fixed.