How wrong they were. The 49ers’ offense found itself in a perfect match-up against a poor rush defense (30th in rush defense DVOA per Football Outsiders) and duly ran all over them. Thanks to Stefan Krüger (@Jav95_) for pointing that one out.
On defense, meanwhile, the 49ers continued their elite play. They sacked rookie quarterback Kyle Allen on seven occasions. Adding insult to injury, they picked the previously interception-free Allen off on three occasions.
The 49ers’ defensive game plan was radically different from that of the week before. Having played man coverage on close to 54% of passing plays against the Redskins, Robert Saleh called for zone coverage on almost 87% of passing plays against Carolina.
On passing plays, he mixed up middle of the field open (MOFO) and middle of the field closed (MOFC) coverages significantly, with just under two-thirds of the coverages called the latter. He did call more MOFC coverages on third downs than he has for much of this season. This seemed to be aimed at limiting Christian McCaffrey’s impact in the passing game, with two players often focussing on McCaffrey on crucial downs.
Saleh also blitzed at his lowest rate of the season, trusting his four-man rush to do the damage against the Panthers’ beleaguered offensive line. Even with Trai Turner returning, the Panthers’ offensive line was overmatched.
Looking ahead to #Panthers-#49ers and SF’s DL vs. Carolina’s OL isn’t a fair fight per PFF.— Akash Anavarathan (@akashanav) October 23, 2019
Bosa/Ford/Buckner/Armstead should FEAST on Sunday. Olsen better stay in to chip/block. pic.twitter.com/gRf649umWc
The Panthers and Allen struggled with the 49ers’ defensive unpredictability. Plays that they schemed up expecting to find cover 3 were met with split field coverages. Furthermore, plays that were designed to beat the coverages they were called against were mostly handled exceptionally well by the 49ers’ defense.
Resultantly, as has been the case all year, the 49ers’ coverage and pass rush combined to inhibit the opposition offense severely. Allen managed an NFL quarterback rating of 28.9 as the Panthers ticked along at a sub-optimal 3.7 yards per offensive play.
The film analysis in this article will focus on the sacks and interceptions of Allen when pass rush or impressive coverage had a crucial contributing role. As such, Nick Bosa’s mind-boggling interception will not appear; look out for Rich Madrid’s (@richjmadrid) breakdown, where he looks in depth at Bosa.
The 49ers first sack of the day came on the Panthers’ first third down of the match, third and three. After disguising their intentions at the snap, the 49ers called cover 3, with an “LOU” rotation of the safeties (Left, Outside). This is commonly called cover 3 sky. This got Jimmie Ward in Christian McCaffrey’s area of the field. Since he returned from injury, the 49ers have often used Ward against their opponents’ favourite receivers on third downs.
Kwon Alexander has to play a “robot” technique, which means he must look for crossers as the weak hook/mid-read coming from the three-receiver side of the formation. He plays deeper than Fred Warner, the strong hook defender.
Seeing this look, Allen identifies that Ward is likely to be isolated at the sticks against McCaffrey, who is running a return route (the same style of route the Rams tried to hit Ward with twice). Ward’s inside help will open to the three-receiver side.
However, Ward plays it really well, staying patient and not over-chasing inside. Warner meanwhile, having opened to the two-curl combo on the three-receiver side, lets Allen’s eyes take him towards the ball. He then gives Ward initial inside help. McCaffrey is doubled. Allen sees this late, and having stared down, his chosen target is forced to pull the ball down.
Simultaneously, the defensive line has managed to create a mess around Allen. Though on the ground, Buckner creates problems around Allen’s feet. Bosa, having threatened a bull rush initially to shorten than the edge, recovered from slipping to plant the panicking Allen onto the turf. Coverage locked down Allen’s favourite target giving the pass rush time to get home.
Arik Armstead’s first sack of the day was another coverage sack. On third and five, the 49ers once again disguised their intentions pre-snap. Ward dropped back into deep centre field just before, as the 49ers were playing a cover 1 rat. The “rat” was Warner, playing in the low hole. Once again, the 49ers’ coverage was impressive. This was particularly the case in the middle of the field, where Allen was keen to go with the football. Warner, K’waun Williams, and Jaquiski Tartt shut down Jarius Wright and Greg Olsen.
As Allen attempted to work further through his progressions, the defensive line struck. Dee Ford bull-rushed Taylor Moton towards his quarterback. Armstead hit the club-arm to cross the right guard’s face, before one-arm bull-rushing centre Matt Paradis back. He then chased Allen down.
Emmanuel Moseley’s first NFL interception was an impressive display of mental processing. The 49ers were playing cover 6. To the field, where Moseley was playing, they were playing 4-read (quarters). Moseley had a deep quarter. However, initially, they showed a cover 3 shell, and this may have been what led Allen to make the throw. He knew he was facing zone coverage because no one followed Wright crossing the formation.
Moseley had to read the routes of the inside receivers, particularly the number two receiver. When the number three receiver went to the flats, Moseley would have been thinking the Panthers may have been trying a flood concept, with the number two receiver running a corner route and the number one receiver running vertically. Moseley would have had the vertical route.
However, there was also the possibility that the Panthers were running a slant-flat or, more likely, a curl-flat combination. The latter is a great call against cover 3. The vertical route inside will take away Moseley’s support. It has a similar effect against quarters - isolating the cornerback.
Despite that, Moseley played it superbly. He recognised that the number two receiver was running vertically as well as reading Allen’s drop. Moseley hit the top of his drop with the receiver 5-6 yards into his route, so Moseley read the quick game. He sat on the curl accordingly, showing excellent processing and recognition. When the throw came in, he made the play.
Armstead’s second sack of the game came when the Panthers attempted a concept that has beaten the 49ers defense in the past - the go/post paired with a slot wheel. This type of long-developing play was one that had the time to hit against the 49ers in the past two seasons.
On this occasion, however, the 49ers play it brilliantly. They once again call cover 3 sky with a LOU rotation. Williams, playing as the seam-flat defender, has to carry the wheel route from Wright. Moseley mid-points the two verticals excellently from his deep-third, and Ward offers inside help on the post from the number one receiver.
In front of them, before the combination can even develop properly, the pressure affects Allen. On the right-hand side, Bosa uses a long arm to turn the corner and clears Dennis Daley’s outside hand with his free hand. Simultaneously, Armstead has blasted past Turner with a devastating bull-rush.
Bosa’s second sack of the match came on one of the 49ers’ two blitz calls against the pass. Williams was blitzing from the nickel spot, with a three-deep, three-under coverage behind.
The Panthers were once again trying to hit the post-wheel combination into the boundary. Alexander dealt with McCaffrey’s wheel with ease, however, and Moseley shut the post down. Warner also took away the potential hot receiver.
Upfront, Bosa attacked half-man, blasting beyond Daley with a bull-rush. Buckner followed him after beating Greg Van Roten. The play was over before it had a chance.
Bosa’s third sack of the day came with the 49ers playing cover 3. On this occasion, there is a “RITA” safety rotation (Right, Inside). This is often called cover 3 buzz.
They have kicked the coverage towards the three receivers. Resultantly, Ward is playing more of a mid-read role than a weak hook and plays deeper than Warner, who is again the strong hook player. It is essentially identical to the coverage called on Bosa’s first sack and takes away over routes.
Warner does a great job dropping into the window of the two over routes from the three-receiver side, taking them both away. Ward waits for the deeper route.
As Allen looks for those routes, Buckner comes free on the end-tackle stunt. Though he misses the sack, he flushes Allen. Bosa comes free to record the clean-up sack.
The final play in this analysis is Richard Sherman’s interception. Though the 49ers once again threaten cover 3, they are playing cover 6. With Sherman playing to the field, he is on the 4-read (quarters) side of the coverage.
Sherman tweeted after the match that the Panthers like to call dagger plays. These are effective against both quarters and cover 3 normally. Against quarters, they clear out the inside safety who would typically rob the dig route, thus isolating the cornerback. Against cover 3, the vertical route can take the cornerback away, leaving a chasm over the top of the intermediate players for the dig.
Allen looks straight to the dagger. Sherman was clearly anticipating it, reading the vertical route of number two. Armstead’s bull-rush up front against Turner created pressure and prevented Allen from leading his receiver in-field. Sherman was sitting on the dig and waiting to undercut it. With the ball heading behind the receiver, it came straight to Sherman, who made no mistake.
The 49ers’ defense once again showed its quality. The coverage was routinely sound, taking away Kyle Allen’s favored options on crucial downs. That gave the four-man rush the time it needed to hit home and disrupt the quarterback.
That coalescence of coverage quality and pass rush will continue to give the 49ers’ defense an edge over offenses, especially when it is so dominant in short-intermediate areas. Fred Warner, Kwon Alexander, K’waun Williams, Jimmie Ward, and Jaquiski Tartt have shone in this facet of the game all season. Of course, when they come up against better quarterbacks, this will be tested further. To date, however, it looks a real problem, as quick games are shut down whilst deep passes are rendered impossible by the rush and playmaking ability of Richard Sherman and the quality of Emmanuel Moseley. Suffocating pass defense is the product.