Film From the Field House: How the 49ers’ Defensive Line Can Continue to Generate Victories

This year has given the San Francisco 49ers' defense a series of body blows. It's suffered season-ending injuries to star players, causing the defensive roster to become as thin as wet tissue paper.

But defensive coordinator Robert Saleh has found a way to scrape together wins, holding the Los Angeles Rams to under 200 yards passing and just over 100 yards rushing.

The secret to Saleh's success starts with a stout, powerful, and speedy defensive line.

Defensive line play is not a factory line counting output numbers. If a star player isn't racking up tackles and sacks, the Twitterverse might shout that the player isn't producing or isn't worth the money.

Great defensive line play is not all about statistics and is often overlooked.

Take rookie defensive tackle Javon Kinlaw for example. He hasn't notched his first career sack and has only 13 combined tackles. On paper, he does not seem worthy of a first-round selection. The film, however, tells a much different story.

1st Quarter - 3rd and 8 at the LAR 44 (10:08)
On this play, Saleh had linebacker Fred Warner fake an A-gap stunt and then dropped into coverage. The 49ers only sent four men to rush Goff, but it was enough to cause an incomplete pass.


Defensive end Dion Jordan went wide at the snap, which forced Rams' left tackle Andrew Whitworth to bounce outside. Whatever protection the Rams called told left guard David Edwards to take two steps inside. These two small nuances opened up the B-gap for Kinlaw Edwards got his left hand on Kinlaw, but it didn't help, and Kinlaw was able to pressure Goff.

Saleh needs to continue to call stunts that put Kinlaw in winnable one-on-one matchups.

2nd Quarter - 2nd and 6 at the SF 26 (11:39)

Fortunately for the 49ers, Rams' quarterback Jared Goff is not known for having Hermes' winged shoes. While the 49ers' defense kept Goff in the pocket, they did have a handful of edge errors that allowed the Rams to gain chunk yardage.


The Rams' called a fantastic counter run to wide receiver Robert Woods early in the 2nd quarter. The play pulled right tackle Robert Havenstein down the line to clear a path for Woods.

Defensive end Kerry Hyder did not diagnose the play right, blew right past Woods, and removed himself from the play.

A seven-yard gain is not a game-changer, but it did reopen an old wound in the 49ers' defense.

Saleh needs to drill into his edge defenders to keep New England Patriots' quarterback Cam Newton in the pocket. Overshooting, overcommitting, or playing a soft edge will invite Newton to run or make a play downfield. Edge discipline is key to victory on Sunday.

And Don't forget Arik Armstead

Veteran defensive lineman Arik Armstead is carrying the load of the defensive line.

Thus far, he's played 283 defensive snaps this year, playing most of his time as the LEO and seeing time at defensive tackle. He's missing Bosa, Thomas, and Ford. Yet, he's still finding ways to make plays that set his teammates up for stops. Any idea that Armstead isn't good enough or somehow is at fault for mobile quarterbacks is wrong.

Armstead made back to back plays on the Rams' third possession of the game, tackling running back Darrell Henderson for a one-yard gain and then breaking up a screen pass to tight end Tyler Higbee.

Saleh was asked about both plays during his press conference on October 22, 2020, and shared insight into why Armstead was able to be effective on both plays.

"To answer your question, it comes from both, experience and film study. He studies film more than anybody, at least on the D-Line, that I've ever been across. He does a great job leading the group and bringing pointers for those guys and really talking at all three levels with linebackers and DBs. So, having him and his knowledge and his need for more knowledge, rather than just what the coaches give him, is a testament to him and why he's deserving of the success he's had."

Armstead will continue to draw more double-team blocks, which will ultimately free up Kinlaw for more one-on-one battles.

There was plenty of positivity in the 49ers' win over the Rams that head coach Kyle Shanahan and Saleh hang their collective hats upon. However, there are also areas the team needs to improve. But the team finally has a foundation, which was lacking during the first five weeks of the season.

All images courtesy of NFL.com.
All statistics courtesy of Pro Football Reference unless noted.

• Bret Rumbeck
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  Bret Rumbeck
  Bret Rumbeck has been writing about the 49ers since 2017 for 49ers Webzone and 49ers Hub. He is a Turlock, CA native, and has worked for two members of the US House of Representatives and one US Senator. When not breaking down game film, Bret spends his time seeking out various forms of heavy metal. Feel free to follow him or direct inquiries to @brumbeck.
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