49ers game review: With Cowboys next, defense needs to tighten up (paywall)
“First, Thomas bit on a stutter-and-go move by wide receiver Michael Wilson and was beaten for a 33-yard reception down the left sideline. On the next snap, with the 49ers in zone coverage, Thomas moved up to cover tight end Zach Ertz, although linebacker Dre Greenlaw was in the area, and Wilson was left uncovered for a 16-yard touchdown catch.
The 49ers have been using Thomas, who played 21 snaps Sunday, primarily when they move Deommodore Lenoir inside to play nickel corner, a position he shares with Isaiah Oliver.