Around halfway through the 2019 regular season, we presented the idea of survival curves, a new way to look at pass protection and pass rush.
These survival curves describe how often a quarterback faces pressure after holding on to the ball for a certain time after the snap. Back then, the analysis was only in hindsight, as we simply looked at how often an offensive line kept the quarterback clean at various points after the snap. But the important improvement upon usual pressure rates is that the evaluation of the offensive line — and the defensive line for the other side of the ball — is independent of how long the quarterback holds onto the ball.
Analysis of what happened on the field is fun and important, but it's even more important when it comes to projecting what will happen going forward. To that end, we spent some time in the offseason developing a machine-learning model that uses information about offensive and defensive lines to estimate the survival curve when two units play against one another.
[Editor's Note: PFF's advanced statistics and player grades are powered by AWS machine learning capabilities.]
In other words, we are predicting how often and how fast a quarterback will be under duress.
Going into each game, our model is incorporating a lot of features to come up with a prediction:
- The survival curve of the offensive line in prior games (or from last year)
- The survival curve of the defensive line in prior games (or from last year)
- The PFF pass-rush grades of the five offensive linemen
- The PFF pass-rush grades of the pass-rushers and where they are projected to line up
- How the blend of individual grades and team-level survival curves from the past are weighted toward predicting the curve depends on continuity and how far in the past the information lies. Less continuity means the individual grades are weighted more heavily.
- Schematic factors such as how often the defense is projected to blitz and how often the offense is projected to use play action, designed rollouts or six-plus-man protections.
This article is the first of a weekly column that will highlight at least three matchups among the scheduled slate of games: a matchup the offensive line is supposed to dominate, a matchup the defensive line is supposed to dominate, and a matchup that will see a very good offensive line face off against a very good or aggressive defensive line (one that is hard to predict but really interesting to watch, if you will).
Favoring the offensive line: Colts at Jaguars