The same down-based success standard as passing success rate, applied to a player's carries.

Inputs: Down, distance, yards gained and touchdown on plays where this player was the ball carrier.

The same down-based success standard, applied to a player's targets (thrown to him, complete or not).

Inputs: Down, distance, yards gained and touchdown on plays where this player was the targeted receiver.

How a player performed once his team's offense (or the opponent's, for a defender) reached inside the 20-yard line.

Inputs: Every play on file within 20 yards of the goal line (`distance_to_goal <= 20`) this player was involved in. COVERAGE CAVEAT: true field position is only recorded for about a third of plays leaguewide, concentrated in FBS/FCS games -- a player whose games come from a source without it will show thin or missing red-zone splits even if he played plenty of red-zone snaps. This is a gap in the underlying play-by-play data, not a sign he didn't play there.