EPA / Dropback
Expected Points Added, averaged over every dropback (pass attempt or sack) that has a value on file. Positive means the play typically moved the team closer to scoring more than an average play in that situation would; negative means it cost expected points.
Inputs: Each play's EPA (from CFBD's own model for most FBS/FCS plays, or this project's own trained model for a smaller share of other games) averaged over the QB's dropbacks. The dropback count with an EPA value on file (not every play has one) is always shown alongside the rate, and boards require at least 20 such plays before a QB qualifies -- a thin sample was found live to distort rankings otherwise.
Garbage-Time-Adjusted EPA / Dropback
The same EPA/Dropback figure, but plays in a blown-out, non-competitive score/clock situation count for less (35% of a normal play) instead of being averaged in at full weight.
Inputs: Same EPA values as above, reweighted using this project's own garbage-time definition (a 7-tier rule based on score margin, quarter and clock).
Passing Success Rate
The share of dropbacks that were 'successful' by a standard down-based yardstick, regardless of whether EPA is available for that play.
Inputs: Gained at least 50% of the yards needed on 1st down, 70% on 2nd, or the full distance (or a touchdown) on 3rd/4th -- computed from down, distance, yards gained and touchdown, all structured fields.
Garbage-Time-Adjusted Success Rate
Passing Success Rate, with garbage-time plays down-weighted the same way as GT-Adjusted EPA/Dropback above.
Inputs: Same down-based success rule, reweighted by the garbage-time definition.
3rd/4th Down Conversion Rate
How often the QB's pass attempts on 3rd or 4th down actually picked up the first down (or scored).
Inputs: Pass attempts where down is 3 or 4, divided into how many were marked as a first down or touchdown by the play-by-play itself.
Rushing Success Rate
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.
Receiving Success Rate
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.
3rd Down Splits
How a player performed specifically on 3rd down plays this season -- success rate, touchdown rate, and the underlying counting stats, isolated from every other down.
Inputs: Every play on file where down = 3 and this player was involved (passer, rusher, receiver, or a tackle/sack/INT/fumble recovery on defense).
What is "garbage time"?
A 7-tier rule (bigger lead required as the clock runs down) that flags plays happening in a game that is no longer competitive -- e.g. a 30+ point lead right after halftime, or a 12+ point lead inside the final 3 minutes.
Inputs: Quarter, game clock, and the score of both teams at the time of the play. Garbage-time plays are not thrown out -- they count for 35% of a normal play in every "garbage-time-adjusted" figure, so a player who pads stats once a game is decided shows up as such rather than being invisible.
