SANTA CLARA, Calif. _ Reuben Foster, the 49ers' eye-opening rookie linebacker, has a mild sprain to the same shoulder that caused his draft stock to fall.
Foster's AC joint sprain is considered "mild" and different from the rotator cuff issue that required surgery in January, according to a team spokesman.
Foster, already the starting weak-side linebacker, was drafted 31st overall after falling down the draft board amid concerns he might need a follow-up surgery on his right shoulder.
General manager John Lynch said Wednesday: "I talked to him and like Reuben, big smile, said, 'I'm straight.' And, so he's good. He's straight."
Foster's injury is among several to strike the 49ers linebacker corps, which picked up a reinforcement Thursday with the return of Shayne Skov, a Stanford product who's had an on-again, off-again tenure with the club since 2014.
Foster sought light treatment from the medical staff on his right shoulder with about 30 minutes remaining in Wednesday's joint session with the Broncos, returned for 7-on-7 action but not full team drills.
Foster has dealt earlier this training camp with a left-ankle sprain and a right-foot issue, none of which appear serious.
"It's not bothering me because you've got the adrenaline rush flowing," Foster said about his ankle after Friday's exhibition win at Kansas City. "You just try to be out there because you love the football game. So things and nicks that hurt, you just want to go out and fight that battle and play and don't worry about an ankle."
Foster, an Alabama product, worked his way into the starting lineup through a consistent stream of "flash" plays this training camp, including four interceptions early on and nearly one in Friday's exhibition opener at Kansas City. He made a one-handed interception in a one-on-one drill Wednesday before getting hurt on a run play.
