Reference
Terminology
The jargon used across the site, in plain terms.
Expected Points Added — how much a play changed the offense's expected scoring outcome, given down, distance and field position.
The share of plays that gained enough yardage to be considered "on schedule" — roughly 40% of yards to go on 1st down, 60% on 2nd, 100% on 3rd or 4th.
Completion Percentage Over Expected — a quarterback's actual completion rate minus what a league-average passer would complete on the same throws, given depth and target separation.
A named, coach-attributable style of offense or defense (e.g. "Shanahan Outside Zone," "Fangio two-high") — transcribed from film-based research, not a statistical cluster.
Rushing Yards Over Expected — Next Gen Stats' per-carry yardage above what a league-average back would gain given blocking and defender positioning.
Offensive EPA per play minus defensive EPA per play allowed — the single number Wal-Bel's ratings are solved from.
Whether a pick would have beaten the closing point spread, not just predicted the winner. See Method for exactly how Wal-Bel does here.