An Overview of the San Francisco 49ers Defense
After playing championship-caliber defense for three consecutive seasons, the 49ers backslid a little in 2024. They brought back former defensive coordinator Robert Saleh in hopes that he would rally the troops. Instead, the defense face-planted in 2025.
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The San Francisco defense was mediocre against the run and finished in the middle of the pack in points allowed, but the pass defense was atrocious, with a glaring lack of big plays. Their 16 turnover were tied for 23rd; they were dead last in sacks with 20; and four teams allowed a higher completion percentage.
The shortcomings can not be blamed on Saleh, who will continue in the coordinator role. A tight salary cap had them in a tough spot to begin with, and the unit was hammered by injuries. The team was thrifty in free agency, adding some guys who will contribute and possibly start. They used four middle-round draft picks on defense, picking up an edge, tackle, corner, and linebacker. The biggest additions, however, will be getting the centerpiece of their defense (Fred Warner) and both starting edge defenders back from injury. On paper, this unit looks to be significantly better than last year's edition.
San Francisco 49ers Defensive Linemen
The team selected Mykel Williams eleventh overall in 2025. He started the first nine games before a torn ACL ended his season. Despite leading the team's edge position in snaps over those nine games, his rookie campaign was uneventful from a statistical perspective, at 11-9-1.
At six feet five and 260 pounds, Williams is a ball of grand potential with a big wingspan and outstanding traits. He entered the draft after his junior year at Georgia, so at age 21, it is no surprise that he got off to a slow start. Williams still has room to grow both physically and technically, and the team still believes in him. The question is, will he be able to step up his game less than a year after the injury?
When healthy, Nick Bosa is elite from both NFL and fantasy perspectives. He racked up nine tackles, eight assists, two sacks, and three turnovers in about two and a half games before tearing his ACL in week three last year. Bosa missed virtually all of 2020 after a week-one injury. He has at least nine sacks and three turnovers in each of his other five seasons, and can be counted on for decent tackle totals as well.
The injury happened early enough that Bosa should be ready for Week 1. That said, he may not be 100% early in the year, especially mentally. Once he is fully physically back and has regained confidence in his knee, a return to top-12 form is imminent.
The team needs their starters to be healthy because they are thin behind them. Third-round rookie Romello Height will compete with journeyman-type Sam Okuayinonu and Patriots 2023 second-round pick Keion White for playing time in the backup role.
White is an interesting prospect in that he had a strong 2024 in New England. That season, he finished with 56 stops, 5 sacks, 2 forced fumbles, and 5 batted passes. Interestingly, he lined up mostly as a tackle that year, where he was clearly more effective. As an edge defender in his other two seasons, White vanished, combining for 44 tackles and 2 sacks.
It was puzzling that the Patriots shipped him to San Francisco instead of putting him back where he could be a factor. On the other hand, it is understandable that the 49ers played him outside because that was their desperate need when they acquired him last year. Let's see if Saleh recognizes what he has and moves White inside.
Considering what the 49ers have at tackle, moving White should be a no-brainer. Last year's fourth-round pick CJ West, and former Cowboy Osa Odighizuwa are penciled in as the starters. Both are decent players, but neither is a difference-maker. In fact, the team has been looking for such a player since letting DeForest Buckner escape in 2020. There are not many bodies on the depth chart behind West and Odighizuwa, so maybe that is the plan.
Alfred Collins fills out the lineup at nose tackle. He is a solid anchor for the run defense, but is not an IDP factor. Collins saw action on fewer than 500 snaps last season, posting 17 combined stops and 1 sack.
- DE Nick Bosa – Perennial top-12 when healthy
- DE Mykel Williams – Long-term potential with short-term concerns
- DE Keion White – Could make an impact from the tackle position
- DE Romello Height – Should see spot duty as a rookie
- DE Sam Okuayinonu – Will compete for backup snaps
- DE Cameron Sample – No impact expected
- DT CJ West – Marginal impact expected
- DT Osa Odighizuwa – Potential depth in leagues starting two tackles
- NT Alfred Collins – No impact expected
- DT Gracen Halton – Developmental rookie