49ers DE Nick Bosa Suffers ACL Tear

Further testing on Nick Bosa‘s knee has produced an unwanted outcome. The 49ers will be without their top pass rusher for the rest of the season.

Bosa was believed to be in the clear regarding an ACL tear after initial tests, although head coach Kyle Shanahan left the door open to other serious injuries. An MRI has revealed that initial optimism was misplaced. Bosa did in fact tear his ACL yesterday, ESPN’s Adam Schefter reports.

Schefter adds this was a clean tear, something which represents only a small consolation. Bosa’s latest injury occurred in his left knee; that is the same one which experienced an ACL tear in 2020. As was the case that time around, the 49ers will need to play out a lengthy spell with a shorthanded defense.

Bosa recovered in full from his first ACL tear (at the NFL level) and only missed four total games across the following four seasons. After going down in Week 3 of the current campaign, however, the All-Pro is in line for another lengthy rehab stint. No other ligaments were damaged, Dianna Russini of The Athletic reports. That will help lessen Bosa’s recovery timeline, but he will still be forced to miss the remainder of the campaign.

After managing to deliver a string of healthy and highly productive seasons, Bosa managed to reset the EDGE market shortly before the start of the 2023 season. The five-time Pro Bowler inked a five-year extension averaging $34MM per year. At the time, that represented the highest AAV for defensive players and non-quarterbacks around the NFL. The bar has since moved on both fronts, but Bosa obviously represents a major element of the 49ers’ financial plan for the near- and long-term. The impact of losing him to another ACL tear cannot be understated.

Another three years remain on Bosa’s contract. He will return to his role as an impact starter once healthy, but in the meantime the 49ers will proceed without him. San Francisco has first-round rookie Mykel Williams in place as the team’s other first-team defensive end. He has logged a 69% snap share to date, and that figure could increase moving forward. Trade acquisition Bryce Huff is also in the fold, along with Yetur Gross-Matos, Tarron Jackson and Sam Okuayinonu. 

That group will be tasked with helping to maintain the 49ers’ strong start on defense. San Francisco sits at 3-0 so far in 2025, and with nearly $26MM in cap space a short-term addition could be sought out via trade or free agency. In any event, the team’s expectations have been dealt a blow with the news Bosa will not be in the fold the rest of the way.

Defensive coordinator Robert Saleh‘s unit has thrived early on in his return to the Bay Area. The 49ers rank fourth in total defense and third in yards allowed. San Francisco has only managed five sacks to date, however, with Bosa accounting for two of them. Finding a way to replace his production will prove to be a key storyline for a team still dealing with numerous injuries on offense.