Nick Bosa's participation in the San Francisco 49ers' offseason program was cut short by a low-grade hamstring strain suffered early during organized team activities. The 49ers won't take any chances, which means he won't return to practice until training camp in late-July.

The coaching staff knows what it has in Bosa. It spent a lot of time studying and getting to know the young pass rusher leading to the draft.

Head coach Kyle Shanahan discussed Bosa with reporters on Tuesday and was asked what his impression of the rookie has been so far.

"For not being out there very much, I've been very impressed," Shanahan responded. "He's been one of the guys. He's not too loud, doesn't try to stand out but also doesn't sit there and hide in the corner. He's one of the guys. I think he's fit in very well.

"I think he's very attentive in his meetings. I think he enjoys football. He's not a guy who's falling asleep in the meetings just because he can't practice that day. He enjoys watching it. He enjoys watching other people and learning from other people, and he's been handling himself great so far."

Shanahan, like the rest of his coaching staff, does not doubt that Bosa will be able to step right back in when completely healthy. Does his position help with that quick reintegration?

"Yeah, definitely," Shanahan said. "I think there's not as many variables that go into it. You've got to beat the guy in front of you. If you don't know what you're doing, but you beat the guy in front of you every single time, you're going to be alright. There is more to that at another position.

"Everybody wants to be out there and get reps. That's what you need to get better, but we'll get him healthy, and it'll make him hopefully better for him to get reps in training camp."

The 49ers' new defensive line coach, Kris Kocurek, said in May that Bosa is getting a healthy dose of work in the classroom and is taking advantage of his time while sidelined.

"Right now, it's mentally, and then trying to get back healthy and all that stuff," Kocurek said. "But he needs to get as many mental reps as he possibly can. Watching the other guys, it's sometimes hard when a guy gets nicked up and stuff and he has to watch from the sideline to realistically try to put himself in the play, but that's what he has to do right now because he can't go out there physically until he gets a little bit better.