ENGLEWOOD, Colo. -- Just eight weeks ago, Denver Broncos left tackle Garett Bolles promised he was "mentally stronger and physically stronger" than he had been at any point in his previous three embattled seasons in the league.

Five games, 348 total snaps later, and don't look now, but Bolles is the highest-graded Broncos offensive lineman in both pass protection and the running game with performances that are -- so far -- well above his work in the previous three seasons.

How?

"Doing the little things, by watching film, knowing where my hand placements are, doing a lot of hand drills, but mostly just a mental thing," Bolles said. "I spent a lot of time this offseason on the mental aspect, you know, I had the physical, the tools, to take care of the techniques, [but] it was all mental, if your mind is not right you can't play this game.

"When times get hard, you continue to work hard and I feel like that's what I did," he added. "That's what's showing on the field."

This season's version of Bolles is what the Broncos were hoping for when they took him in the first round of the 2017 draft. But it's not the Bolles they got the previous three seasons when he led the league in holding penalties each year. As a result, the Broncos did not pick up the fifth-year option on Bolles' contract, which will now expire after this season.

But this season, Bolles has been one of the most consistent performers on a youthful Broncos team. According to ESPN Stats & Information, Bolles is not only the Broncos' highest-graded lineman in pass block win rate, but also in run block win rate. According to those rankings, Bolles is the only Broncos lineman with a pass block win rate of over 90%.

In five games, none of the Broncos' sacks allowed or interceptions thrown by any of the three starting quarterbacks have been attributed to him.

"I certainly haven't seen what everybody else saw prior to me getting here," Broncos offensive coordinator Pat Shurmur said. "I've been pleased with what he's done. He's tough, durable and knows what he's doing. ... Guys are allowed to change, guys are allowed to improve, and guys are allowed to produce at a higher level than they did in the past. I think he's done all of those things."

Bolles has been flagged just twice this season and coach Vic Fangio disputed one of those penalties. By this point last season he had already been flagged for five holding penalties on the way to 13 by season's end. He had 17 penalties overall in 2019.

Bolles' improvement comes at a critical time for the Broncos. Right tackle Ja'Wuan James opted out of the season before training camp over concerns about COVID-19. James' replacement -- Elijah Wilkinson -- went to injured reserve in September. The Broncos start a rookie at center in Lloyd Cushenberry III.

"I think he's been called for only two penalties, and one of them was a bad call that shouldn't have been called," Fangio said. "I think he's played well, and he's played dinged up, too. He's got an elbow that's bugging him and something else that's bugging him and he's fighting through it. I felt good about Garett coming into this season, I remained in constant contact with him throughout the offseason and knew he was in a good spot mentally and emotionally."

Earlier this season, Bolles admitted he previously let one mistake in a game turn into more. His penalty flags, in particular, often came in clusters. He had four holding penalties in Week 2 last season, three holding flags in Week 7, multiple penalty games in Week 9 and Week 11.

"When something happens, I can't physically take that back," Bolles said earlier this season. "If it happens, I have to let it go and move on the next play."

Bolles said he added 20 pounds before reporting to training camp this summer. He has held up better at times against the edge rushers looking to push him back into the quarterback once he was even slightly off balance. Bolles, Fangio and Shurmur have tossed some of the credit at offensive line coach Mike Munchak. All involved, though, stress that 11 regular-season games remain before the full story can be told.

It could be good timing for Bolles if he keeps this up. Because the Broncos did not engage the fifth-year option on his rookie contract, he will be an unrestricted free agent at a high-demand position by season's end.

"I truly believe with the way coach Munchak coaches, it's perfect for Garett," guard Dalton Risner said. "He's going to call Garett out when he needs to be called out, he's going to uplift Garett when he needs uplifting and he's going to teach Garett. He knows how to teach the game because he's done it. In fact, he's got a gold jacket from doing it."

"I trust him, I believe in him, I know he believes in me," Bolles had said. "I just have to do whatever I can to make him know that he can trust me."