Bosa's day ended early on Tuesday when he tweaked his right hamstring during pass rush drills. He was seen walking around with a limp afterward, and head coach Kyle Shanahan didn't have an update on the severity of the injury while speaking with reporters after practice.
Nick Bosa tweaked his right hamstring during two-on-two pass rush drills just now.
— Grant Cohn (@grantcohn) May 21, 2019
Looks like Nick Bosa tweaked something during the first half of #49ers practice. He sat out team and conditioning drills after some early work in 11 on 11s.
— Chris Biderman (@ChrisBiderman) May 21, 2019
Bosa was one of two big-name pass rushers added this offseason. The 49ers traded for Dee Ford in March and the two are expected to bookend a defensive line which already includes Pro Bowl defensive tackle DeForest Buckner.
San Francisco finished last season ranked No. 22 in quarterback sacks. Buckner led the team with a career-high 12 while Ford racked up a career-high 13 last season with the Kansas City Chiefs. Bosa accumulated 17.5 in just over two seasons with Ohio State.
Running back Matt Breida won't participate in the 49ers' offseason program. Shanahan said he suffered a slightly torn pectoral muscle from a workout in the weight room. The head coach expects Breida to be healthy by training camp.
"It's frustrating for Breida because he can do just about everything," Shanahan said. "We've just got to avoid contact for him, so he can't be out there running with other people on the field. That means he can't do anything until training camp."
Shanahan noted that Breida did not and will not require surgery.
Shanahan also noted that running back Raheem Mostert had a setback with the broken forearm injury which ended his 2018 season early. He had to have surgery again to repair the injury, which has pushed back his recovery by about a month. Like Breida, Mostert should be healthy by training camp.
"He had a little setback with the surgery," Shanahan said. "I'm not really sure what that was. Just in how the bone grows back together. They noticed it early, so they just started it over, which I think cost him about four weeks."
Linebacker Fred Warner also will not participate in the 49ers' offseason program. He underwent a clean-up procedure on his knee but should be ready for training camp. Rookie Dre Greenlaw received significant reps in Warner's place.
"Fred has some residual stuff on his knee that was bothering him when he got back, so we waited a week to see if it would go away," Shanahan said. "It was still lingering. We just cleaned it up."
Tight end Garrett Celek is in the concussion protocol and will not be cleared until at least training camp. The injury occurred during last season's Week-16 matchup against the Chicago Bears. He is also dealing with a back injury.
Rookie wide receiver Jalen Hurd has not practiced due to his recovery from a knee injury. Shanahan said the team wants to make sure he gets a couple more weeks of conditioning before putting him through team drills.
"He didn't start getting cleared to run until a few weeks before the draft," Shanahan said. "To only have him for a week, we want to make sure we get a little bit more to get him in football shape."