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.

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.

How a player performed in the last two minutes of either half -- the clock-management, high-pressure stretch at the end of the 2nd and 4th quarters.

Inputs: Every play on file in the 2nd or 4th quarter with 2:00 or less on the clock this player was involved in. Same field-position/clock coverage caveat as Red Zone Splits above -- roughly a third of plays leaguewide carry a usable clock reading, concentrated in FBS/FCS games.