The 49ers' Injury Math Gets Harder as Nick Bosa Goes Down With a Calf Strain

Nick Bosa didn't get hurt making a tackle. He tweaked his calf doing high knees while warming up for Thursday's walkthrough, Kyle Shanahan said, and now he'll miss a few weeks, according to ESPN's Adam Schefter and NFL Network's Ian Rapoport.

It's bad timing in every sense. Bosa was two games into his return from a torn ACL, with 70 snaps played, and was about to face Arizona almost a year to the day after tearing that ACL against the Cardinals. He's out for that game.

I know he's bummed out, but he'll be back.

Guessing at IR

Teams can bring back only eight players from injured reserve in a season, and the 49ers are already burning through that. Shanahan said several players are in the same spot as Bosa, so the team has to guess whose injury will last longest before deciding who goes on IR. He called it complicated, and the team was leaning toward keeping Bosa off it.

The defensive line list is long. C.J. West, Sam Okuayinonu and Alfred Collins are on IR. Rookie tackle James Thompson Jr. has a high ankle sprain that could cost three to six weeks, and rookie edge Romello Height broke his hand; both are out Sunday.

That leaves Keion White, Khalid Kareem and Ogbo Okoronkwo as the healthy ends, with Vincent Anthony Jr. and Viliami Fehoko Jr. on the practice squad. Mykel Williams could practice next week after his own ACL recovery but can't play before Week 5 in Seattle. On offense, Mike Evans is questionable with a hip injury.