How One Rookie Singlehandedly Fixed the 49ers' Run Defense

This is an incredible stat.

San Francisco 49ers defensive end Mykel Williams (98). | D. Ross Cameron-Imagn Images

Mykel Williams could finish his rookie season with zero sacks, and he still would be the right pick for the 49ers.

Through two games, Williams has been one of the most valuable and impactful players on the team, and yet has recorded just six tackles. The box score simply doesn't reflect how dominant he has been at defending the run.

Fortunately, the advanced stats show his impact. Through two games, opposing offenses have a 25.8 success rate when Williams is on the field, and a 66.7 percent success rate when he's off the field. That's a stark difference.

San Francisco 49ers defensive end Mykel Williams (98). | Stephen Lew-Imagn Images

Why Mykel Williams is so good against the run

When Williams is playing, offensive linemen can't move him. That's why they often double-team him on running plays. And yet, Williams can hold his ground and free up the linebackers behind him to make plays.

Why do you think Dee Winters suddenly is playing like prime Dre Greenlaw? It's because no one is blocking Winters. Williams is keeping him clean so he can do what he does best -- run and hit.

A big reason the 49ers' run defense took such a downturn last season is that the team released Arik Armstead, who had been their best run-defending defensive lineman for years. In fairness to the 49ers, Armstead was breaking down and getting old. They made the right decision in releasing him.

Jacksonville Jaguars defensive tackle Arik Armstead (91). | Morgan Tencza-Imagn Images

But they didn't replace him until they drafted Williams in Round 1 this year. Like Armstead, Williams can shut down the run while playing defensive end or defensive tackle. Unlike Armstead, Williams can contain mobile quarterbacks while playing defensive end. Armstead routinely would let them escape.

Armstead took five years before he became a borderline Pro Bowl player, although he never has been a Pro Bowler. Williams has much more potential than Armstead ever had. Williams should develop into a quality defensive end and a dominant defensive tackle, as opposed to Armstead, who eventually became a full-time defensive tackle. He is much more versatile than him.

If Williams never develops into a dominant pass rusher, he still will have a long, successful career in the NFL, because every team needs a defensive lineman who's a boulder against the run. But as long as he gets to play alongside Nick Bosa and Bryce Huff, Williams should get one-on-one opportunities on third down, which means he could walk into 10 sacks by accident. That's what Armstead did in 2019.

Williams is just scratching the surface of what he can become.