Method · coverage_epa@v1

Coverage

Expected points added allowed per dropback on plays where the defense got no sack and no hit. With the rush removed from the play, what is left is mostly coverage.

The filter, exactly as it runs

qb_dropback = 1 AND sack = 0 AND (qb_hit = 0 OR qb_hit IS NULL)

Where this is arguable

Unpressured plays still include hurried throws, so this is not pure coverage.
Good coverage creates pressure by making quarterbacks hold the ball, so the two cannot be fully separated. That circularity is real and worth stating.

These are the objections I already know about. If you have a better one, or you think a different threshold tells a truer story, say so and I will re-run it with your numbers and publish what comes back.

Version 1. Older versions are never deleted, so a piece that citescoverage_epa@v1 stays reproducible after this definition is revised. Source: Data: nflverse (nflfastR), CC-BY 4.0