The Buffalo Bills’ offense surgically picked apart the San Francisco 49ers in a 34-24 win on Monday Night Football. Josh Allen earned AFC Offensive Player of the Week honors with a four-touchdown, 375-yard passing performance. To add insult to injury, the Bills had multiple “walk-in” touchdowns against the 49ers, with a wide-open receiver waltzing untouched to the end zone. Why were those touchdowns so easy? Let’s turn to the tape and see why.
1st-and-Goal at SF 5 - J. Allen pass short right to C. Beasley
The Bills have 11 personnel on the field following a defensive holding penalty that gives them a first down five yards from the end zone. Devin Singletary and Lee Smith are the back and tight end, respectively, and the core trio of Diggs-Beasley-Davis are the receivers.
Before the snap, the Bills line up in a 2x3 empty formation. As the team is lining up, Allen makes an alert call, with the new play bringing Singletary into the backfield before the snap. 49ers nickel Dontae Johnson, seeing the way the new formation is closer to a 1x3 look with the linebackers leveraged over Singletary, crosses the formation to the side with Smith, Beasley, and Davis, and has the safety and linebackers bump over one gap.
At the snap, the Buffalo routes on the offensive right side create a natural conflict between 49ers defenders. The safety seems like he’s in man coverage on Smith, while Johnson and Richard Sherman look like they’re in some sort of pattern-matching combo coverage. What happens is that Smith’s route to the sideline and Davis’s route up the seam create two obstacles between Sherman and Beasley’s quick hitch. Beasley lines up at the target, Allen is looking at him the whole time, and fires the ball into place before Sherman can close.
In the Erhardt-Perkins terminology of the New England Patriots playbook (the system offensive coordinator Brian Daboll came from), this three-man route combination is called Diner:
These crossing routes, as mentioned, create a natural pick play when executed from a bunch formation against man coverage. They also form a three-pronged triangle of options—effective when attacking a zone defense!
1st-and-Goal at SF 4 - J. Allen pass short right to D. Knox
This play was set up by head coach Sean McDermott’s faith in his offense—and analytics. After Buffalo’s first drive sputtered on a failed 4th-and-goal attempt, the Bills faced a 4th-and-1 at the five-yard line. They could’ve kicked a field goal, but chose to try and convert the down once again. Devin Singletary’s outside run was well contained, but it still moved the chains.
This time, the Bills are in 12 personnel. Dawson Knox and Lee Smith line up off the left tackle, Singletary is in the backfield, and Stefon Diggs and Gabriel Davis are split out to the right.
Right before the snap, Knox starts motioning toward the right—almost a similar way to Isaiah McKenzie’s jet sweep plays. At the snap, Josh Allen holds the ball out for a play fake to Singletary. After pulling the ball, he turns and throws immediately to Knox. Both receivers are laying blocks, so this throw was clearly designed for Knox. From there, it’s all down to the individual efforts of Diggs and Davis blocking and Knox outrunning the flat-footed linebacker and defensive end.
The reason this play works so well is because it looks shockingly like a split-zone run (also called split flow). See, the entire offensive line is blocking outside zone to the left side of the field (where Singletary runs to after the play fake). In coming across the formation toward the defensive end, Knox could be executing a trap block on him, which would open up a big running lane for Allen on the backside of the run blocking.
With the play fake, and good eye discipline from Allen, the play also can look like a zone read—the defensive end is supposed to stay home, ride the mesh, and funnel the QB up the middle if he keeps the ball—which he does!
So the defensive end and the linebacker are both seeing keys that tell them “RUNNING PLAY”. By the time Knox clears the backfield, both players are tripping over themselves, and Knox has a head of steam.
2nd-and-9 at SF 23 - J. Allen pass deep left to I. McKenzie
This play is set up with the Bills leading 17-10 in the third quarter. Facing a 2nd-and-9 at the 23-yard line, the Bills are confidently in field goal range—and a ten-point lead would be nice. But they want to take a shot at the end zone, and the 14 point lead that comes with it, and they come in with this design. Three receivers (including Isaiah McKenzie in place of Cole Beasley), Dawson Knox, and Devin Singletary are on the field.
If you’ve been a Bills fan in the last three years, you know McKenzie’s role on the team—jet sweep guy. I’d actually take it another step further and say that he’s the closest thing the Bills have to a Canadian Football League slotback on their roster. Shoutout to my favorite player Weston Dressler, and to the CFL fans in the comments—hope I’m not too off track with the following explanation.
See, one key difference between the CFL and the NFL is that NFL players going in motion cannot be moving forward (i.e. toward the end zone) at the snap, while CFL players can. In the CFL, you’re going to see a ton of players taking big running starts before the play starts, with the idea being they can run routes at full speed right away. The jet-sweep role McKenzie plays is the closest you can get to that in American Football.
On this play, the Bills are essentially using McKenzie as a slotback—putting him in motion toward a wheel route, but having him run it full speed by showing that jet motion first. By the time he crosses the line of scrimmage, he’s hit top gear.
The other reason this play works is Gabriel Davis, running a pretty aggressive pick on the play. He’s technically running a post route, but puts just a bit of shoulder into the safety on his stem. Davis’s tight alignment also leaves lots of running room for McKenzie to accelerate toward the sideline. Lastly, the safety also takes a bad step downhill at the snap—maybe he was planning to run blitz? Either way, he’s totally out of position on one of the easiest throws of Josh Allen’s career.
This play features two two-man route combinations: Peel (a post-wheel) and Illinois (an in-under combo).
Post-wheel is a very popular Cover-3 beater, because the player running the post will pull away the deep-third defender, and the wheel route enters the vacated space. The other defender in that area usually focuses on short hook/curl assignments, which makes him a bad matchup against a deeper pattern like a wheel route. Illinois, a two-man levels concept, gives Allen easy high-low reads on the backside of the play. Dawson Knox’s under route even enters the vacated space from McKenzie’s wheel route, giving Allen a safe checkdown option if it weren’t open.
2nd-and-10 at SF 28 - J. Allen pass deep right to G. Davis
I mentioned before how a certain area of the field is “shot” territory for the Bills to aim at the end zone just for kicks. Once again the Bills are in field goal territory, now leading by ten. Upping that to a 13-point lead wouldn’t really help the game situation much, so the Bills would like points here. Hence, they’ll try aiming directly at the end zone.
This play is a blown coverage by the 49ers. After the game, Richard Sherman explained that “we were in Palms coverage. Two into the flat. I adjusted, but we had a few busts on the play. It’s unfortunate. The motion put us in a look we hadn’t seen before.” Doug Farrar has an excellent breakdown of this play, and I recommend you read his article. I’ll attempt to give a shorthand version of that explanation here.
What is Palms coverage? It’s a type of Cover-2 defense, so where you have two deep safeties. You have a cornerback positioned on the outside, matched up against a receiver. What’s happening is the defenders are reading the slot receiver on that side of the field. If his route is short, the outside cornerback will jump it, and the safety takes care of the outside receiver in the deep part of the field. If the slot receiver’s route goes deep, the safety is responsible for him, and the cornerback keeps the outside receiver in man coverage. It’s also called “2 trap”, because you’re setting a trap for the QB. Your coverage looks one way, then shifts based on the route being run.
So how does it play out here? The Bills start in a 3x1 look with a running back in the backfield, but motion Cole Beasley across the formation into the slot, showing a 2x2 formation. Gabriel Davis runs a Go route, while Beasley runs a hitch with a little razzle-dazzle.
At this point, Beasley already had well over 100 receiving yards and a touchdown, and so the 49ers are all keenly aware of him. Meanwhile, Sherman watches Beasley run a short route and stays in the flat, as per his palms coverage assignment. But the safety doesn’t pick up Davis. Like, at all.
The play-side route combo is, I think, what we’d call “Gotti”—a go/option combo. With Beasley, I can never be certain how much he’s freestyling on a play, so I think this fits.
On the backside, Stefon Diggs is definitely running a go route, and Devin Singletary is running into the flats. I can’t tell exactly what Dawson Knox is doing, though—it kinda looks like a deep out, but then he turns it upfield at the end.
Given how this play fits the theme of the rest of these touchdowns, I’m going to say this was another tendency the Bills identified and attacked in their game plan. They were reading one step ahead from start to finish, and the 49ers never had an answer for their attack. That’s pretty much the theme of this game: Josh Allen and Brian Daboll, and their strong supporting cast, setting the tone all evening and forcing San Francisco to react. The outcome was never in question.