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How Nick Bosa has helped carry the 49ers defense through four games

Bosa put on a show against the Seahawks this past Sunday. He’s among the league leaders in every meaningful statistical category for pass rushers

Seattle Seahawks v San Francisco 49ers Photo by Michael Zagaris/San Francisco 49ers/Getty Images

They say you never truly appreciate something until it’s gone. The 49ers season felt like it was over the second Nick Bosa went down with a season-ending injury against the Jets during the second quarter of Week 2 last year.

Bosa is back and better than ever. In four games, per Sports Info Solutions, Bosa has hurried the quarterback 11 times with five quarterback hits. PFF tracks how often a player beats their defender as well as charting their “win percentage.” Bosa is near the top of the league in both, despite being double-teamed. Bosa’s win percentage of 19.8 is tenth in the league.

Check out this graph from Next Gen Stats to get an idea of how often Bosa is winning, despite seeing extra help:

That doesn’t include a tight end or a running back chipping Bosa, which feels like it happens every other play.

Bosa makes this defense go. The season numbers for the 49ers look average, thanks to a few differences. First, it seems as though San Francisco relies on more man coverage than ever. Under Robert Saleh, the defense ran Cover 1 224 times last season.

This year DeMeco Ryans has already run Cover 1 65 times in only four games. So he’s going to play man coverage, bring five rushers, and bet that you cannot get open or block long enough. So far, it’s paid off.

The breakdown below features a lot of Bosa being...Bosa. The last play I highlight shows Bosa beating three defenders. That’s an extreme example, but, as is the case with most teams, nobody can block No. 97.

The 49ers are around league average in defensive success rate this season. I explain why man coverage has cost the team a few long gains. When you look at their numbers on a down-to-down basis, the defense is seventh in plays per drive, 11th in yards per play, and ninth in third-down conversion rate at only 33%. Yet, they’re well above average, and they get off the field. So, what gives?

Allowing the fourth most first downs by penalty doesn’t help. But the Niners aren’t generating turnovers. The ball isn’t bouncing their way. Only 2.2% of their drives have ended in a turnover, tied for last with the team coached by Urban Meyer.

Today’s theme is how you do on a per drive basis, and the 49ers are dead last in turnovers per drive. Yes, worse than the Jaguars. This year San Francisco is averaging .023 turnovers per drive. Last season, that number was .108. In 2019, they were seventh at .143 turnovers per drive.

There isn’t anything I’d do differently on defense if I were Ryans. Tight coverage is there. Bosa is winning, and the rest of the team has generated enough pressure. More often than not, turnovers are about luck. Regression to the mean should benefit the 49ers’ defense during the rest of the season or at least the remainder of the first half.

Thanks to that regression to the mean, Bosa, Jimmie Ward, and Ryans’ aggressive scheme, I’m confident the Niners will finish this season as a top-10 unit. Here’s video evidence as to why: