The 49ers suddenly have five prominent players who could be in danger of missing Week 1.
The list starts with rookie defensive end Nick Bosa, who sprained his right ankle during practice Wednesday and had an MRI. It includes running back Jerick McKinnon (knee), cornerback Jason Verrett (ankle), slot corner K’Waun Williams (knee) and center Weston Richburg (knee).
Coach Kyle Shanahan said Bosa will miss the entire preseason while the team is “hoping for (his return) Week 1.”
Said Shanahan: “I believe there’s three components of a high ankle sprain, which makes it an official high ankle sprain. He does not have all three of them. That’s all the science I know on that. Basically it’s a minor high ankle sprain.”
General manager John Lynch went on KNBR radio Friday morning and had high praise for Bosa’s work on the practice field after a minor hamstring injury prevented him from participating in the bulk of the offseason program.
“The great thing I can tell you about Nick Bosa, he’s been dominating practice out here on a daily basis,” Lynch said. “He’s a game-changing type player, everything we hoped and expected. We have to get him right for this season.”
The 49ers are suddenly thin at defensive end after adding reinforcements in the offseason. Dee Ford is expected to miss at least another week after getting platelet-rich plasma injections in his knee for tendinitis he suffered early in training camp. Arik Armstead (calf) and Ronald Blair (groin) have missed the last two practices, though their injuries are day to day, Shanahan said.
McKinnon, who returned to practice this week after suffering an ACL tear just over 11 months ago, experienced soreness in his surgically repaired knee in his two practice sessions and will also receive PRP injections in hopes of expediting the healing process.
The initial plan is for McKinnon to sit out the next two weeks, giving him 18 days to prepare for Week 1 following his PRP treatment.
“And if he’s ready, that would be great,” Shanahan said. “And if not, we’ll be patient with him and come back and expect one of our other guys to step up.”
McKinnon could be a candidate to start the season on injured reserve, Shanahan said, where he could and come back eight weeks into the season. That way, McKinnon wouldn’t take a spot on the active roster following final cuts. McKinnon can’t revert to the active physically unable to perform list because he was activated off that list this week to return to practice.
“Jet’s the guy we gotta be careful with,” Shanahan said of McKinnon, who was expected to begin training camp healthy but had a “flare up” that led to starting on the PUP list.
Shanahan said the team initially feared Verrett’s injury was much worse but his talent should secure him a future with the 49ers. The 2014 first-round draft pick of the Chargers has played in just four games since making the Pro Bowl in 2015 and missed all of last season with a torn Achilles. He signed a one-year deal with San Francisco in the spring and was expected to compete for a starting job, though he spent the early portion of training camp getting back into playing shape.
Williams had his knee scoped recently, Shanahan said, and is also expected to miss the entire preseason. Williams has been one of the team’s most steady defensive backs over the past two years. His absence leaves second-year pro D.J. Reed and Emmanuel Moseley as remaining nickel cornerbacks.
Finally, Shanahan said center Weston Richburg was also in danger of missing the season opener against Tampa Bay on Sept. 8. Richburg has been ramping up his workouts on the side field while on PUP following surgery to repair a quad/knee injury suffered Week 4 last season. He played through the injury and made 15 starts after signing a five-year, $47.5 million contract, which is the third largest for a center in the NFL.
Veteran Ben Garland, who played for Shanahan with the Atlanta Falcons, has been practicing with the starters in Richburg’s place.