The San Francisco 49ers suffered a devastating setback when star defensive end Nick Bosa was ruled out for the season with a torn ACL. Losing the former Defensive Player of the Year is a crushing blow to a defense built around his relentless pass rush and game-changing presence. But in true 49ers fashion, the focus has already shifted to the players who must step in and keep the standard high.
Head coach Kyle Shanahan acknowledged the challenge but stressed that the team’s identity won’t change. “You don’t replace Nick Bosa with one guy,” Shanahan said. “It’s going to take a group effort. But that’s what this team is about—next man up.”
One of the first names in line is rookie first-round pick defensive end Mykel Williams. The first-year pass rusher has already flashed potential, showing quickness off the edge and the ability to disrupt plays. While he won’t replicate Bosa’s production, Williams’ growth could accelerate with more snaps and responsibility.
Opposite him, veteran depth will also be tested. Bryce Huff becomes critical in generating pressure. His Week 2 performance, where he recorded five quarterback pressures, proved he can create problems when given the chance.
On the interior, Kalia Davis and Jordan Elliott will be tasked with anchoring the defensive line up the middle. Their ability to collapse the pocket from within can help ease the pressure on the edge rushers. A stronger push inside will also make life easier for San Francisco’s linebackers, led by Fred Warner, to continue flying to the football.
The secondary will also feel the ripple effect. With less natural pressure on quarterbacks, cornerbacks like Ji'Ayir Brown and rookie Upton Stout may face more time in coverage. Stout has impressed in big moments, including a clutch third-down stop against Arizona in Week 3. His continued emergence could help stabilize the back end of the defense.
No one player can replace Bosa’s impact, but the 49ers have built their roster with depth for this very worst case scenario. The defense may look different. They may need to rely more on blitzes, disguises, and collective effort, but San Francisco has already shown they can still get the job done, holding Kyler Murray and the Cardinals offense to just 15 points in Week 3.
For the 49ers, the loss of Bosa is a gut punch, but not a death sentence. The “next man up” mentality will define this franchise in 2025. If players like Williams, Huff, and Stout continue to rise, San Francisco can still field a defense capable of carrying them deep into the season.