Trevon Diggs, and the difference between ballhawks and shutdown cornerbacks

Trevon Diggs is a ballhawk, but he won’t be a shutdown cornerback until he learns to stop biting on double moves.

One reason the 49ers were beating the pants off the Cowboys early in their wild-card game was that San Francisco receiver Brandon Aiyuk was demolishing Dallas cornerback Trevon Diggs on double moves and short, sharp cuts. As productive as Diggs has been this season as a ballhawk — he had 11 interceptions in the regular season, the most for any defender in 40 years — he can get got on these kinds of routes, and that’s been the case all season.

This would have been a big gain had Jimmy Garoppolo not overthrown his target…

…and this 37-yarder was a big play, as Diggs struggled to keep up with Aiyuk through the route.

In the regular season, Diggs allowed 55 catches on 96 targets for 1,016 yards, and five touchdowns to go with those 11 picks, and per Sports Info Solutions, four of his touchdowns allowed came on deep double moves. It’s a byproduct of Dallas’ high rate of Cover-1 — man coverage with a single deep safety — which leaves cornerbacks on relative islands depending on where the deep safety goes.

Here’s Broncos quarterback Teddy Bridgewater’s 44-yard touchdown pass to Tim Patrick in Week 9, and this is exactly the problem. Patrick hit Diggs with a quick stutter down the boundary, Diggs had no help up top, and that was that.

Diggs is in his second NFL season, so it’s entirely possible that he’ll learn to deal with double moves, and become the shutdown corner his interception numbers would lead you to believe he already is. As for now, it’s a pretty serious flaw, and it’s showing up a lot in this game.