While most pundits and analysts pointed out the league-low 20 sacks the San Francisco 49ers had last season, subsequently suggesting the Niners needed to find pass-rushing help entering 2026, it wasn't hard to overlook how porous the run defense was, too. Especially in the interior.
Neither of San Francisco's two high-profile interior draftees from last season, defensive tackles Alfred Collins and C.J. West, made much of an impact defending against the run, and the 49ers allowed a troubling 4.3 yards per carry over the course of 2025.
While other offseason additions certainly carried more weight and attention, inking former Illinois defensive tackle James Thompson Jr. as an undrafted free agent shouldn't go unnoticed.
The 6-foot-5, 308-pound defender made a name for himself as a run stopper, registering 41 tackles, three of which for a loss, to go along with two sacks over the course of his final collegiate season.
While Thompson will likely need to showcase some interior pass-rushing ability to stand a chance at the 53-man roster, it wouldn't be a complete shock to see him impress in training camp and potentially carve out a niche role on the depth chart.
James Thompson Jr. could be 'secret sauce' to fix 49ers' run defense
The 49ers are hoping Collins takes a next-level leap in year two, and they're also banking on a 2026 rookie, Gracen Halton, emerging as a quality interior defender as well. But depth is still a need, and that's where Thompson will have a fighting chance to secure a spot by Week 1.
From Thompson's NFL.com scouting report:
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.
Again, Thompson will have to refine his pass-rushing abilities to stand a remote chance. But to boast some prowess as a quality run stopper, not unlike how former defensive lineman Evan Anderson made his way to the 53-man roster during his rookie 2024 season, Thompson could be part of the solution that cuts down on the Niners' interior deficiencies.
At the very best, perhaps Thompson overtakes someone like West on the depth chart.
Either way, the undrafted rookie might have a slightly better leg up on his back-end competition, and it wouldn't be a massive shock to see him impress enough during training camp and into the preseason en route to locking up a spot on the 53-man roster.
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