3. Jayron Kearse
Was Jayron Kearse the Cowboys worst performer against the 49ers? If not, he was no worse than second on the list. Kearse hasn't looked like the indispensable Swiss Army knife he was in 2021 and 2022, and Sunday night was a culmination of his slow start to the season.
Mishaps in coverage, filling gaps against the run and tackling aside, Kearse was flagged for two needless penalties that cost the Cowboys.
His offsides on third down is just about the most boneheaded penalty a player can commit in that situation and it looks worse given his experience. Later in the game, Kearse committed a taunting penalty after Donovan Wilson laid a massive hit on Christian McCaffrey over the middle.
Both Wilson and Kearse were flagged, but there was nothing else Wilson could have done. NFL rules make it impossible for defenders to make that play without a flag. Kearse's taunting is a different story. It gave the 49ers a fresh set of downs after a third down stop and it occurred with Dallas trailing by two touchdowns.
The Cowboys secondary was carved up on Sunday night, but Kearse's poor start to the season deserves more attention. He's one of the biggest trash-talkers on the roster and hasn't backed it up one bit.