The Denver Broncos didn’t lose their first game of the year due to one man, but without a doubt, the offensive line’s play was less than stellar on Sunday.

That was headlined by the struggles of Garett Bolles, the second-year left tackle who held and tackled opponents twice in the game, allowing one sack.

According to Pro Football Focus, Bolles allowed not only the sack but five pressures on Case Keenum as well, earning a 40.5 overall grade.

“I let one mistake happen, then I let it [happen] again, and again and again,” Bolles said of not trusting himself in the Broncos 27-14 loss. “I can’t let those things happen, especially playing left tackle in this league and protecting No. 4 (QB Case Keenum) and being on the edge by myself.

“I’ve got to trust myself by making sure I’m doing the proper footwork, hand placement, trusting [Offensive Line-Tackles] Coach [Chris] Strausser and what he teaches me every week, and apply those in the game,” Bolles continued Monday. “I need to do a better job of that. Yesterday’s performance is just unacceptable.”

At least Bolles is taking ownership of his ghastly play, and he wants to improve from there, obviously.

The problem is, at Year 2 in the NFL, Bolles should be over making massive mistakes. Last season, his rookie campaign, Bolles was up-and-down nearly every other week. He had four games last year in the 50s, as rated by Pro Football Focus, but none as low as last week. It’s a bit surprising he played so poorly — and could have been partly due to playing veteran Terrell Suggs — because Bolles was very solid in the first two weeks, both in pass and run-blocking, scoring a 72.4 overall each week.

For Denver’s starting left tackle, the good news is he should be able to bounce back. The bad news is, for a No. 20 overall pick, he’s not playing nearly well enough on a consistent basis.

Denver (2-1) faces Kansas City (3-0) on Monday Night Football at Mile High Stadium. If Bolles struggles again, it could continue to make it difficult for Case Keenum to find open receivers and build the missing, all-important chemistry with his new team.