Thomas didn't play college football in 2020, opting out of the season due to COVID-19 concerns. San Francisco selected the former Michigan cornerback in the third round of this year's draft.
With Emmanuel Moseley and Dontae Johnson ruled out for Week 14, Thomas made his first NFL start, playing 93 percent of the defensive snaps. He had his ups and downs. But, of course, many tend to point towards the downs during quick evaluations.
For the 49ers, it was an encouraging outing for the rookie cornerback, who had only played 20 defensive snaps before Sunday's 62.
"I was really encouraged," general manager John Lynch said Thursday on KNBR's Tolbert, Krueger & Brooks show. "People see the one touchdown that was reversed, and then they see the slant-and-go, and they say he had a bad game. You know, I was actually encouraged, just watching the nuance of his game, kind of how he handled himself, how he approached [the game] after a tough play like that. I thought he tackled well throughout the game. He was in the right place."
Lynch is correct about the tackling, per Pro Football Focus. While Thomas's overall defensive grade hasn't been impressive this season, his tackling grade has been. In fact, he and teammate Deommodore Lenoir own the two highest tackling grades (Lenoir, 83.9; Thomas, 82.4) among rookie cornerbacks from the analytics site.
"I thought Ambry had some encouraging snaps out there, and it was his first time with that much action in the NFL," defensive coordinator DeMeco Ryans said after Thursday's practice. "For his first game, I thought he did some good things, he did some encouraging things, and it's a lot for him to grow from, a lot for him to learn from as well, with him being out there as much as he did.
"And one thing I liked about Ambry, he didn't blink. He had some penalties, gave up a play, but he didn't blink. He just got right back out there. He continued to compete, and I love that about him. I liked his attitude throughout the game. I like that he was flying around, so he did something things there for us that he can definitely grow from."
The 49ers believe Thomas has what it takes to be a starting NFL corner. Many were quick to label the rookie as a potential bust after he was inactive for five of the team's first seven games. The selection of Thomas was made with the future in mind, though. Injuries, however, have forced him to contribute sooner than initially hoped.
"Ambry's a really gifted player," Lynch continued. "He can run, and he can play the football when he's in the air. And he's got poise when he does that, so those are two really good qualities. There's other things that will come with experience, and you'd like to be able to get that experience when the stakes aren't so high, but that's not the position that we're in.
"He got thrown out there, and I know this: he'll be better for having gone through that experience, and I think he'll get better each and every week."
Moseley won't be eligible to return until Week 17 at the earliest, when the 49ers host the Houston Texans. If Thomas continues to play "encouraging" football, opportunities will present themselves. For the 49ers, this final four-game stretch and playoff push may depend on some of their younger players stepping up.
"Rookies, they have to play, and they're going to have their ups and downs when they do, particularly at that position," Lynch added. "But if they can find a way to keep getting better, which both [Thomas and Lenoir] have done in practice, now they're getting to do it on the field, and I was really proud with the way they acquitted themselves versus Cincy."
You can listen to the entire conversation with Lynch below.