49ers HC Kyle Shanahan Reveals Key Defensive Improvements Are Needed

Where the 49ers need to improve.

Jan 3, 2026; Santa Clara, California, USA; San Francisco 49ers head coach Kyle Shanahan before the game at Levi's Stadium. Mandatory Credit: Sergio Estrada-Imagn Images | Sergio Estrada-Imagn Images

How the San Francisco 49ers made the playoffs without Nick Bosa and Fred Warner in 2025 still feels like a miracle.

Losing both Bosa and Warner in Week 3 and Week 6, respectively, meant the 49ers had to find a way without their two biggest defensive stars for more than half the season.

2025 showed that the San Francisco 49ers could compete without both Bosa and Warner, but were obviously a lot worse off defensively and struggled to maintain consistency throughout the season in critical moments on both sides.

Nov 19, 2023; Santa Clara, California, USA; San Francisco 49ers linebacker Fred Warner (left) talks with defensive end Nick Bosa (right) during the fourth quarter against the Tampa Bay Buccaneers at Levi's Stadium. Mandatory Credit: Darren Yamashita-Imagn Images | Darren Yamashita-Imagn Images

How then defensive coordinator Robert Saleh, who is now the head coach of the Tennessee Titans after one year back in the City by the Bay, helped the 49ers win certain games with rookies and depth pieces may be one of the best coaching displays in recent years.

Head coach Kyle Shanahan didn't anticipate the season to begin that way, but the draft and free agency strategy means they have more roster numbers as contingencies.

The highlight was that they traded for Osa Odighizuwa and brought back Dre Greenlaw. They tendered defensive lineman Sam Okuayinonu, and they also drafted Romelo Height, Grace Halton and Ephesians Prysock.

“I think we need to be better on defense all-around in terms of, we got fortunate last year, we didn’t play a ton of quarterbacks, so I think that helped us not get as exposed, but we went in a little light, just because of losing guys in free agency and stuff," said Shanahan on the Tom Tolbert Show.

"I knew we were going in light, but I didn’t know we would lose Nick Bosa and Fred Warner. Doing that made it really tough. I think Robert Saleh did a great job, I think our guys rose to the challenge and did a great job, but we weren’t good enough.

"And I think what we’ve done in free agency, what we’ve done in the draft, the guys that did get all this experience last year who are better now, bringing Raheem Morris, I think that will be the challenge, to be that much better. Not just in the run, but everywhere.

New defensive coordinator Raheem Morris has plenty to work with this season, but the exact timeline for Bosa and Mykel Williams remains unclear. There are valid questions about whether the defense can stay healthy and generate consistent pressure on the pass rush, and hold its own in matchups with stronger opponents on their schedule.