One of the knocks on Nick Bosa's draft profile coming out of Ohio State was that the defensive end might have trouble staying healthy in the NFL. He was coming off a junior year limited to three games because of a core muscle injury. Bosa's high school playing days also ended with an injury.

Bosa missed most of the 49ers' organized team activities and all of the June minicamp due to a low-grade hamstring injury. He had been full-go in training camp up until Wednesday's practice when he went down with an ankle injury.

Ian Rapoport of NFL Network initially stated that the injury wasn't too serious, but general manager John Lynch and head coach Kyle Shanahan joined KNBR on Thursday morning and stated that the injury was more significant than reported.

Lynch and Shanahan don't like hearing that Bosa might be injury-prone because they don't believe that to be the case.

"We don't feel he is injury-prone," Lynch said during that Thursday-morning interview. "He had a core-muscle deal in his last year of college, and he took that year and decided to get healthy. Yesterday, he had a big human being fall on his leg while he was engaged with someone else. Some of those things, that's football. You can't prevent that.

"We're thrilled with what we have in Nick Bosa. We're going to get him right, and he'll be a great player for a long time in this league."

After Thursday's practice, Shanahan was asked by reporters if there is any level of concern surrounding Bosa's ability to stay on the field. The short answer: No.

"Not with me because I go back to his history and I think the guy stayed on the field throughout college," Shanahan said Thursday afternoon. "I mean, look, he played 12 games his freshman year, I think 13 (it was actually 14) his sophomore year, I think he played in three his next year, and he had a surgery to repair his, I think his oblique, that probably was a pretty good decision for him, too.

"So, when you go back to that decision, he played game-in and game-out until that year, and now we have a guy come in, and someone landed on his leg. And that doesn't make me say someone's injury-prone because he had one serious injury in college and he tore his ACL sometime in high school like 60-percent of the players out there."

That last statistic was an exaggeration, of course, to get his point across. At least, I assume Shanahan was overstating it.

Bosa has been impressive during training camp. He has looked dominant more often than not, and Lynch has already noted that the rookie looks like a polished football player. As has quarterback Jimmy Garoppolo, cornerback Richard Sherman, tackle Joe Staley, and others.

"He's a really good football player, and he's polished," Lynch said last weekend during a segment on NFL Network. "A lot of guys, even if you pick them at two, there's a getting-used-to period, but he's such a polished football player. He's giving them fits already."

Said Garoppolo, "He gets there so quickly. And how he plays the run and pass, I don't think that goes as noticed as it should. For a rookie to be able to do both of those, it's pretty impressive."

Added Sherman, "Nick came in really sharp. He came in executing, came in beating guys. He looked like a veteran. He looked like a 10-year (player).

"They were probably going to rest him anyway. I would imagine he wouldn't have played too much unless the starters were playing. But we're really excited for what we have in him. He's an incredible player, an incredibly smart player. He has all the tools at his disposal.

"He's something everybody should be excited about. I think that John and them hit a home run with him, even at the second pick. I think he's undervalued. He's a monster."

Then you have Staley praising Bosa during a conversation with Matt Barrows of The Athletic.

"He's a lot more polished than a lot of rookies that come in," Staley said. "He comes from a family that understands football, and he understands D-line play and is a lot further along with his understanding of the game and what it takes."

The 49ers remain hopeful that Bosa will be healthy by Week 1. Shanahan and the coaches have to make sure Bosa gets the rest he needs to meet that goal.

"The last thing he wants to do is get hurt," Shanahan added. "He's trying to go out there and play with it. He wants to come back tomorrow. But he had an over 300-pound man land on his leg, and it was very fortunate that we didn't lose him for the year."