Balance of Power: Best Possible Rotation for the 49ers' Defensive Line


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I’ve killed a fair share of electrons sharing my excitement for the San Francisco 49ers’ defensive line. Over two seasons, I’ve called them the defense’s anchor, North Star, nearly unbeatable and other fancy phrases to capture my hope.

Yet, in both seasons, I’ve been let down by the overall play from the defense, despite some strong individual performances from the defensive line.

Yes, DeForest Buckner is one of the best and most underrated defensive linemen in football. No, Arik Armstead did not play poorly last year, despite the misgivings of a former beat reporter.

We learned that head coach Kyle Shanahan and defensive coordinator Robert Saleh lacked threating edge defenders, resulting in an ineffective pass rush and a soft underbelly in the defensive front.

Though, Shanahan and defensive coordinator Robert Saleh deserve more credit than what they’ve been given for what they were able to do with the scrap heap of the NFL. The 49ers finished 2018 with a better pass and run defense than the Kansas City Chiefs. The 49ers allowed 300 fewer yards on the ground, six fewer rushing touchdowns, 642 fewer passing yards, and 62 fewer completions.

This season, Saleh has five first-round draft picks - including two new edge defenders - ready to patrol the line of scrimmage. For the sake of this commentary, we need to agree on a few points.

First, I believe the 49ers will keep the following interior defensive linemen on the 53-man roster:

  • DeForest Buckner

  • Arik Armstead

  • Sheldon Day

  • Solomon Thomas

  • D.J. Jones

  • Kentavius Street

I am looking forward to seeing Kentavius Street in action. As you know, Street suffered an ACL tear during his pro day, though the 49ers drafted him 128th overall during in 2018. Street spent last year on the reserve/non-football injury list.

Second, I’m going to include the edge defenders in my rotation. Otherwise, we’re just cycling a few interior linemen, which isn’t all that interesting. Obviously, rookie Nick Bosa, Dee Ford, Ronald Blair, and Mark Nzeocha will man the edges for the 49ers this season.

Third, I’m not going to get into specific down-and-distance line-ups. I have no idea who Saleh will put on the field when it’s third-and-15 or in a nailbiting, late-game situation when the team needs a huge stop. Frankly, I think you put your best men on the field and let the chips fall where they may, but I’m not interested in what-if, two-months-down-the-road hot takes.

Saleh has highly-talented personnel and a rare opportunity to mix, match, and rotate his defensive line with confidence during a game.

Further, he can remove Thomas from an edge position, which he and Shanahan have tried for the last two years with little success. There’s no rational explanation to play Thomas outside the 4-technique.

As much as I’d like to sit down with Saleh and savor every little nuance of his defense, he’s yet to invite me over for beers. So, I don’t know every small wrinkle or adjustment he has in the playbook, and neither does anyone except the gentlemen in the defensive film room.

I do know Saleh has used 4-3 over/under fronts with various adjustments and combinations. This season, with a supposed emphasis on the wide-9, we may see Saleh shift to traditional over/under fronts; this means he’ll have four defensive linemen at the line of scrimmage and three linebackers off the ball.

Saleh said it himself back in May:

Philosophically, has your defense changed at all with the change at defensive line and the talk of more wide-nine? Has anything changed from your standpoint about what you want to get accomplished?

“No. We might look different, but philosophically, the overall foundation of the defense hasn’t changed.”

Robert Saleh. May 29, 2019

4-3 Over Front – 3-technique tackle shifts to the strong side

LEO (open or weak side): Bosa

1-Technique: Armstead/Thomas

3-Technique: Buckner

Strong Edge: Ford

4-3 Under Front – 3-technique shifts to the weak side

LEO (open or weak side): Bosa

3-Technique: Buckner

1-Technique: Armstead/Thomas

Strong Edge: Ford

I like shifting Buckner in both fronts, only to force the offensive line to choose who it might want to double-team. If Buckner stunts inside to the A-gap, and he takes the guard and center with him, it leaves Bosa or Ford one-on-one with the tackle. That’s a match-up I’ll take each day of the week.

Further, I believe Thomas could easily substitute in for Buckner for a series and find success.

Saleh’s also used three-man fronts from time to time, which is where we might see some of the reserve interior players shine.

Below is an example from Week 10 against the New York Giants. Marsh was aligned wide on the weak side, Buckner was in a 4i-technique, nose tackle Sheldon Day was squarely over the center, outside linebacker Dekoda Watson was also in a 4i-technique and Sam linebacker Malcolm Smith was covering tight end Evan Engram.

Week 10: 49ers vs. New York Giants – 1st Quarter, third-and-5 at the NYG 49 (5:39)

In a front such as this, I expect the following personnel:

3-Man Over/Under Fronts

Sam: Ford

Strong-side edge (4 or 5-technique): Ronald Blair

Nose: D.J. Jones

Weakside Edge: Street

Will: Nzeocha

Blair had a breakout season in 2018, notching 8 sacks, 15 hurries, 21 tackles, and 20 run stops. He doubled or nearly tripled his output from the 2016 and 2017 seasons, which makes him an ideal player in a substitute package.

Last year’s dismal pass rush tallied a whole 275 quarterback pressures of any kind, resulting in a whopping two interceptions. Compare the same statistics with the Chicago Bears defense that had 342 total pressures of any kind and led the NFL with 27 interceptions.

I’d also encourage fans to not view Saleh’s scheme through myopic eyes. Fronts and techniques can be altered to fit a player or situation; there’s nothing in a playbook that is set in tablets of stone. Mixing the look and the front is what causes problems for an offense.

These are pivotal points to take into this fall: It’s not always about sacks; it’s about turning the opposing quarterback’s bowels into liquid Jell-O. I want him thinking that Buckner, Ford, and Bosa are all around him, even if these men are still sipping a cold halftime drink in the comforts of the Levi’s locker room.

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