SANTA CLARA — San Francisco 49ers defensive end Nick Bosa will miss multiple weeks after injuring his calf warming up before Thursday's walkthrough, head coach Kyle Shanahan confirmed, ruling the star pass rusher out for Sunday's game against the Arizona Cardinals.
"We can't say exactly, but I'm guessing around a few weeks," Shanahan said of Bosa's timeline, via David Bonilla of 49erswebzone.com. Shanahan said Bosa was warming up before the walkthrough when he injured his calf, adding "I know he's bummed out, but he'll be back." It is unclear whether it was his right calf, Shanahan said he wasn't sure. Bosa had returned from a torn ACL in his right knee suffered in Week 3 last season — almost exactly a year ago against the Cardinals — and played 70 snaps over the first two games.
"Losing Bosa was rough yesterday," Shanahan said. "I mean, losing six out of the 10 D-linemen in the last two weeks that have made our team is a little unusual. I don't think I've been a part of that, so that has been different." The 49ers also ruled out rookie defensive end Romello Height, who needs hand surgery, for Sunday. Defensive tackle C.J. West (knee), defensive end Sam Okuayinonu (foot) and defensive tackle Alfred Collins (patellar tendon) are on injured reserve, while rookie defensive tackle James Thompson Jr. has a high-ankle sprain that will keep him out multiple weeks.
San Francisco is still deciding whether to place Bosa on injured reserve. Shanahan noted only eight players can return from IR during the season and the team already has several players designated to return. "He's right there at that point, along with a couple of other guys that are all in the same boat," Shanahan said. "Because of the number we have on [injured reserve], we won't be able to do all of them. So we've got to decide, and we're just trying to guess which ones will go longer, which ones have the chances of being sooner, and it's just a guess. They're all really in the same boat, so we've got to decide that by tomorrow." The depth crunch follows C.J. West being placed on injured reserve with a knee bone chip requiring surgery.