The 49ers made some subtle alterations to their defense via free agency and the draft. And they are hopeful those changes help push them from being the top-13 group they were last season to one that cracks the top 10.

For that to happen, though, they must stay healthy. That was not the case last year when Nick Bosa, Mykel Williams and Fred Warner missed significant time with injuries.

All three are on track to return, and if they stay on the field, it increases the chances the 49ers experience a big push defensively.

Here is a look at where things stand with the 49ers’ defensive depth chart, after free agency and the draft:

Defensive end

Starters: Nick Bosa, Mykel Williams

Reserves: Romello Height, Keion White, Sam Okuayinonu, Mikail Kamara, Andrew Farmer, Cameron Sample, William Bradley-King

The skinny: It’s still a jolt realizing the 49ers managed just 20 sacks last year. Not to make excuses but losing Bosa and Williams clearly played a major role. Knee injuries limited Bosa to three games and Williams, their 2025 first-round pick, to nine games. Both are on track to be back in 2026. That will make a massive difference. Height is expected to offer immediate help as a rotational rusher.

Bottom line: If this room stays healthy, there’s no chance the 49ers finish with 20 sacks this year. If they get back to the normal way they pressure quarterbacks, it changes everything about their defense.

Defensive tackle

Starters: Alfred Collins, Osa Odighizuwa

Reserves: CJ West, Evan Anderson, Sebastian Valdez, Bryson Eason, James Thompson Jr., Gracen Halton

The skinny: The addition of Odighizuwa, whom the 49ers acquired in a trade with the Cowboys, adds plenty of punch to their interior pass rush. He has a knack for getting heat on the quarterback, and along with Collins and West, a pair of 2025 draft picks, helps fortify that part of the 49ers’ defense for the interim and future.

Bottom line: The 49ers have done a solid job rebuilding the interior of their defense and in the process laid the groundwork for a young, athletic, productive rotation.

Linebacker

Starters: Fred Warner, Dre Greenlaw

Reserves: Nick Martin, Tatum Bethune, Garret Wallow, Jaden Dugger, Jalen Graham, Milo Eifler, Luke Gifford

The skinny: Much like their defensive line, the 49ers were ravaged by injuries at linebacker. Specifically, Warner. He played just six games due to a dislocated and broken right ankle. Again, that is a personnel loss that teams can’t easily overcome. He’s back, as is Greenlaw, who returns on a one-year contract, and as a result, the 49ers’ linebacker room looks whole again.

Bottom line: This room looks solid with Greenlaw and Warner back in the fold, but Martin can really strengthen this group by stepping up in his second season. Bethune and Wallow also have chances to earn rotational roles.

Cornerback

Starters: Deommodore Lenoir, Renardo Green, Upton Stout

Reserves: Jack Jones, Nate Hobbs, Eli Apple, Darrell Luter Jr., Ephesians Prysock, Siran Neal, Tre Tomlinson, Jakob Robinson, Derrick Canteen

The skinny: The 49ers’ cornerback room took a decidedly Raiders-like look with the additions of Hobbs and Jones, who played well together in Las Vegas. Both have starting experience, but even if they just bolster the depth, it could go a long way. When healthy, Hobbs has been a solid slot cornerback, although staying on the field has been a challenge for him. Green and Stout could have a fight on their hands holding onto their starting jobs.

Bottom line: It remains to be seen how much Jones and Hobbs will affect starter snaps, but their additions clearly bolster the top-to-bottom quality of the 49ers’ cornerback room.

Safety

Starters: Malik Mustapha, Ji’Ayir Brown

Reserves: Marques Sigle, Darrick Forrest, Jalen Stroman, Patrick McMorris

The skinny: Mustapha has developed into a solid starter after being selected in the fourth round, but Brown needs to be more consistent. Could a path open for Sigle to take his job? He played relatively well after being drafted in the fifth round last year.

Bottom line: Again, if the pass rush improves because players stay healthy, it’s going to help the entire defense, including the back end. The personnel is on hand to make it work at a decent clip.