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49ers vs Rams Defensive Film Review Part 1: Instant adjustment up front shuts down Rams’ rushing attack

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After an ominous opening drive, the 49ers’ adjustments up front shut down the Rams’ rushing attack and destroyed their game plan

NFL: San Francisco 49ers at Los Angeles Rams Orlando Ramirez-USA TODAY Sports

Seven plays. Seven runs. Seven points. The Rams’ first series was a devastatingly efficient start to the game against a 49ers defense that had been dominant all season. Players were missing assignments, bamboozled by motion and misdirection in a manner threatening to derail things early.

Such a start may have sent other teams into panic mode. The 49ers’ defensive game plan was being taken apart against an offense that managed 69 points in their previous two matches.

This is 2019. And the 2019 49ers don’t panic. They went to the sideline, the coaches made adjustments and the defense was sent back to work. No further points were scored and the Rams were cowed into submission in their own house.

It was the Rams’ plans that were derailed.

The 49ers trusted that their defense could stymie the Rams’ rushing attack and would be far too good for Jared Goff and the Rams’ passing offense. The 49ers’ ball control and defense first approach was an aggressive measure, perfectly in tune with the roster construction. The 49ers played their game in the Rams’ house, whilst the Rams were forced to change. Some statement.

In Part 1 of this defensive film review, the focus will be on how the 49ers shut down the Rams’ ground game after the opening series. In Part 2, I will primarily look at the 49ers’ defensive performance on third down.

The Opening Drive

Whilst Sean McVay’s approach may have ultimately been grounded in fear of the opponent, there can be little doubt that the Rams’ execution during the first drive was superb. They managed to generate alarming yardage on the ground. There were three key reasons:

First, the Rams created unexpected and significant east-west movement along the offensive line; tackle Andrew Whitworth was often blocking nose tackle D.J. Jones.

Second, the Rams influenced the second level defenders to move gaps with motion. This movement often turned out unnecessary because different offensive players would subsequently block or motion back across the formation. Rather than resulting in adding another gap to one side of the formation with motion, which needed to be accounted for by defensive movement, no gaps were added. The movement left the 49ers shorthanded on the side the Rams intended to attack.

Third, the Rams often specifically attacked the bubble (in this instance the B-gap) between nose tackle D.J. Jones and defensive end Nick Bosa. With the 49ers playing quarters coverage, the Rams played on the conflict created for the overhang defender, who was responsible for this B gap as well as the slot. Bosa stayed wide as the force defender thus creating a wide B gap. The overhang defender was often himself placed into conflict by motion, making him late to arrive at his responsibility.

The Rams’ first run of the game demonstrated all these principles.

The Rams dialled up a counter run unlike to those Kyle Shanahan has called this season. Designed to attack the obvious cut-back lane between Jones and Bosa, McVay used motion to stress the 49ers’ defensive rules. Up front, the first thing to note is that Bosa is ignored by Whitworth, who instead helps Joseph Noteboom manhandle Jones. The design also contributes to giving Whitworth an excellent angle to climb to Fred Warner.

Behind the offensive line is where the true magic happens. Tyler Higbee arrives on a sift block to chop down Bosa, preventing him from compressing the chasm opened up or blowing up the play as an unblocked defender. K’waun Williams is the overhang defender responsible for the wide open gap. McVay affects him with orbit motion, causing him to step back outside instead of closing towards the run. Buckner and Tartt eventually make the stop.

Subsequent runs also utilised certain of the above principles to gash the 49ers defense.

On this play, the Rams again attacked the backside of the 49ers defense. The pre-snap jet motion influences the 49ers’ second level defenders, causing them to move to the left in order to account for the potential extra gap being created on their left side. However, with Higbee sifting back across the formation post-snap, no extra gap was created to the left side. In reality then, the motion merely moved Williams into the box and Tartt out of it, a favorable outcome for the Rams.

Furthermore, it also moved Fred Warner from the backside B-gap into the front side A-gap, which gave Whitworth a much better angle to block him. Jones was once again moved across the formation and Higbee’s sift block took out both Williams and Bosa opening up a sizable gap.

The Adjustment

The big adjustment that the 49ers adopted was to slant their defensive linemen in order to disorientate the Rams’ blocking assignments. This isn't the first time this season the 49ers have attempted to slow an opposing rushing attacking in this manner. They did so against the Buccaneers in week one.

The 49ers also asked the defensive ends to squeeze inside more, to compress the avenues into which the Rams running backs could attack upfield. Behind them, the linebackers, safeties and cornerbacks were tasked with shutting down the Rams’ horizontal rushing attack. With the 49ers mainly playing quarters or cover 6, they didn't have to move much with the Rams motion, and they trusted their cornerbacks and safeties to shut down jet sweeps.

D.J. Jones’ injury also forced the 49ers into a change. Sheldon Day was the obvious choice to replace Jones. However, the 49ers decided that their adjustments required a level of explosiveness that Day perhaps lacked and instead tabbed Solomon Thomas to play nose tackle. His ability to get upfield and transverse gaps instantly caused the Rams real problems.

The Rams attempt to call a similar counter play to the first play analyzed, but the 49ers’ adjustments blow it up. Both Thomas and Buckner slant to the right, exchanging gaps with the linebackers behind them. Thomas was initially aligned at 3-tech. He slanted into the A gap and smashed into the centre, also drawing the guard’s attention. He drove the centre back into the running back’s cutback lane and severely impacted the designed movement to the 49ers’ left the Rams had hoped to generate.

Buckner was aligned as the nose tackle. He slanted across Noteboom who had been manhandling Jones and drove Whitworth into the backfield.

With Thomas and Bucker limiting the Rams lateral movement and resetting the line of scrimmage, the 49ers’ other level players could get to work. Arik Armstead set the edge against Rob Havenstein whilst Kwon Alexander and Tartt ensured Brown had nowhere to go.

On this occasion, Buckner is lined up as the 3-tech. Thomas is the nose tackle. Both slant to the right again as the Rams attempt another cutback style play call to target the backside B-gap. Once again, the movement of Buckner and Thomas causes problems, with Buckner to the fore. He blasts past the centre into the cutback lane and engulfs Henderson. Armstead also dominates the right tackle to assist on the stop.

On the backside, Thomas beat the guard inside before spinning off Whitworth to help finish the play. Bosa also took a much tighter angle inside to reduce the distance between him and Thomas. Alexander covered the area outside Bosa and Moseley (out of shot) also provided protection against the jet sweep with his palms read.

The 49ers again slant their interior players. Thomas slants from the A-gap to the B-gap, with Buckner going from the B-gap to the A-gap. Once again, this clogs up the interior of the Rams’ offense. Thomas ultimately beat Whitworth with his leverage to make the stop. Other significant contributions came from the defensive ends. Bosa takes a very tight path inside, smashing into Higbee to prevent a large cutback lane from opening up in the C gap. This prevented the 49ers’ from being punished for Williams’ hesitation. On the other side, Armstead controlled Havenstein. He essentially two-gapped, allowing Alexander to freelance somewhat.

Additionally, a couple of other big plays were at least in part a product of the 49ers’ defensive adjustments.

The 49ers actually have Ronald Blair at 3-technique here, showing their commitment to quick, explosive players inside. Had this been a running play, the movement on the front-side with Blair and Alexander exchanging gaps looks likely to have created a 1-on-1 in the hole between Alexander and Brown.

However, it is the backside where this play is made. Rather than Bosa being the backside contain player, he gets aggressively into the C gap - squeezing the potential rushing lanes again. This permits Tartt to stay wider as the contain player, giving him a favorable angle against the subsequent screen pass. His recognition, physicality and speed were also on show, as he blew up Everett in the backfield.

Thomas’ sack was also a product of the 49ers’ adjustment. Lined up as the nose tackle in the A gap, it is not unreasonable for the Rams to ask their centre to block back on Thomas on the play action. With Thomas and Buckner again slanting however, Thomas is simply too explosive for the centre to block. He explodes off the ball, ripping beyond him before sacking Goff. The coverage and recognition behind (more on that in part 2) was also exceptional, notably from Fred Warner.


What was most impressive about the 49ers’ adjustments was the speed in which they were made. Robert Saleh credited their offense with sustaining a lengthy drive to allow the coaches time to make the changes, but their proactiveness in making the changes so quickly was laudable. Other teams may have waited another series or two before abandoning their existing plan but not the 49ers.

As well as showing the quality of the 49ers’ staff however, the changes also demonstrated an alternative line-up that we could see more of on the defensive line in future. With Armstead and Bosa capable of beating up offensive tackles outside, a combination of Thomas and Buckner inside offers elite quickness which can seriously impact an offense’s blocking assignments.

While it may not be suitable against offenses focussing on generated north-south movement in the run game, teams attempting to create lateral movement will struggle with Buckner and Thomas slanting against their grain of their blocking assignments. Nonetheless, it is a strategy that has worked against teams like the Buccaneers who favoured double teams inside, throwing them off, and is certainly something I hope to see moving forwards. It also benefits from the smarts and quality of the second and third level players behind.

Ultimately, it is just another possible wrinkle for Robert Saleh to utilise when he sees fit and a very effective one at that. The 49ers’ defense looks increasingly elite.

In Part 2, I will look at the 49ers’ impressive outing on third down and fourth down, focusing on how the quality and versatility of the defense has made high powered offenses look impotent on money downs.