How the 49ers Can Fix their Defense

It gets a lot harder from here

August 23, 2025; Santa Clara, California, USA; San Francisco 49ers defensive coordinator Robert Saleh before the game against the Los Angeles Chargers at Levi's Stadium. Mandatory Credit: Kyle Terada-Imagn Images | Kyle Terada-Imagn Images

Tennessee exposed the 49ers defense; the Titans ran easily, threw over the top, hit and missed wide open receivers. Robert Saleh needs to fix it. The final three opponents all have top seven run games in the last six weeks, and top seven scoring offenses on the year.

Replace Curtis Robinson and Jason Pinnock

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Robinson is a special teams player; against Tennessee, there were plays where he had his back to the ball carrier. He’s been out of position and missed tackles. The Niners clearly need Tatum Bethune back and he returns to practice this week. He’ll improve the run defense and communication.

Pinnock is a journeyman who plays like it. He’s inconsistent and makes mistakes. Given the need to make plays in the run game, particularly in the next two weeks, if Eric Kendricks is healthy, he needs to take the field. Kendricks is an instinctive player against the run, a top 15 linebacker last year according to PFF.

Saleh’s platoon rotation of a big nickel base defense and small nickel with Upton Stout on passing downs is a forced fix based on lack of skill sets at safety and linebacker. Kendricks is a big upgrade in the run defense over Pinnock. If Kendricks is targeted in the pass game, they’ll have to return to DBs and safeties.

Experiment with personnel groups to cover tight ends while stopping the run

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Kendricks may be next up for the big nickel, but he’s a run defender only. Pinnock was a target with a neon bullseye over his head. I would experiment with Darrell Luter Jr.; he has coverage skills and size for the run game.

Another possibility is the Niners recently signed Isaiah Bolden to the practice squad. If he looks good in practice, Bolden has the requisite physical profile at 6-2/205 with 4.35 speed.

After the litany of coverage mistakes on the Gunnar Helm 34-yard touchdown, the Colts and Bears will call that play with first round tight ends Tyler Warren and Colston Loveland. Saleh has to come up with a solution before the playoffs.

Send Malik Mustapha on run blitzes

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The Niners are a top ten defense in how often they disguise coverages; Mustapha is frequently in position to run blitz. He’s a capable run defender, but even if he misses the tackle, the blitz can slow down the ball carrier, and the rest of the defense can converge. For the league’s worst team in sacks, they need to manufacture more tackles for loss.

Against Indianapolis

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Saleh prefers to protect against explosives, but when facing Philip Rivers that isn’t necessary. 17 of his 19 completions last week were six yards or fewer, and nine of those were thrown behind the line of scrimmage. On throws beyond ten yards, Rivers was 2-8 with an interception.

The defensive game plan against the Colts must be loading the box against league rushing leader Jonathan Taylor. The Niners have the league’s worst success rate on run defense since Mykel Williams went down. They need the full defensive line rotation and could have all of the active linemen back for the Colts game.