The San Francisco 49ers spent last season staring at a pass rush problem, but the run defense was a mess, too - especially inside. That’s why undrafted defensive tackle James Thompson Jr. is worth watching closely as training camp approaches.
San Francisco finished 2025 allowing 4.3 yards per carry, and neither of its two high-profile interior draft picks from last year, Alfred Collins and C.J. West, made much of an impact against the run.
The 49ers also managed just 20 sacks, the league low, which naturally pushed the pass-rush issue to the front of the conversation. Still, the interior run defense was a glaring part of the picture.
That opens a lane for Thompson, a former Illinois defensive tackle who signed with the 49ers as an undrafted free agent. At 6-foot-5 and 308 pounds, he built his college reputation as a run stopper, finishing his final season with 41 tackles, three tackles for loss and two sacks.
Thompson’s path to the 53-man roster is clear enough: he’ll need to show he can do more than clog lanes. Interior pass-rushing ability will matter if he wants to stick. But if he can bring the kind of run defense the 49ers lacked a year ago, he has a real shot to make noise in camp and maybe carve out a role.
San Francisco is hoping Collins takes a step forward in year two, and the team is also banking on 2026 rookie Gracen Halton to become a useful interior piece. Even with those hopes, depth remains an issue, and that’s where Thompson can make his case by Week 1.
From Thompson's :
Interior defender with heavy hands and a frame for additional mass. Thompson is experienced and capable of playing in even or odd fronts.
Tight hips limit his bend at the point of attack, creating inconsistent leverage, but the play strength and hand usage are in place. He’ll give effort as a rusher but he lacks tools to create NFL pressure.
Thompson projects as a late-round pick or undrafted free agent.
The comparison that comes to mind is Evan Anderson, who worked his way onto the 53-man roster as a rookie in 2024 by giving the 49ers something they needed inside. Thompson could follow a similar path if his run-stopping translates quickly enough.
At the top end, he could even push someone like West on the depth chart. And if he keeps flashing through training camp and the preseason, it wouldn’t be a surprise to see the undrafted rookie stick.
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