Last season, Patrick Mahomes and the Kansas City Chiefs faced the Buffalo Bills twice — once in Week 6, and again in the AFC Championship Game. In those two games, Mahomes completed 50 of 64 attempts for 550 yards, five touchdowns, and no interceptions. The Chiefs won both games, and the Bills were left to wonder, as good as they were, what they had to do to get past this guy.
Fast-forward to Sunday night in Week 5 of the 2021 season, and it was clear that Bills head coach Sean McDermott and defensive coordinator Leslie Frazier had the answers to the test. The Bills came in as the NFL’s best defense by far in Football Outsiders’ metrics, though FO’s opponent adjustments haven’t fully kicked in yet, and naysayers could say that in facing the Steelers, Dolphins, Washington, and the Texans, that defense hasn’t really been tested.
We can now throw that story away. In a 38-20 thrashing, the Bills limited Mahomes to 272 passing yards on 54 attempts and 34 completions, and while Mahomes threw two touchdown passes, he also threw two interceptions, and his yards per attempt average of 5.04 was the lowest of his career. His 70.9 passer rating was the second-lowest of his career, behind the 62.8 he put up in 2018 against a Jaguars defense worlds better than it is now, and his Adjusted Yards per Pass Attempt of 4.11 was also the lowest he’s ever posted for a single game in his NFL career.
One season after being dominated by Mahomes twice, the Bills came back with a fire and fury their defense had not shown before against this esteemed opponent.
“I think Leslie Frazier and the staff do a really good job,” McDermott said after the game. “The players buy in every week. They come in hungry whatever day they are first in the building. They embrace the game plan and they really play together. It is fun to watch them play because they are a very unselfish group and they work hard during the week. Their successes are by no accident.”
The Bills were able to present Mahomes with a heavy dose of two-high safety coverage, because when they do so, they can also stop the run, and running against two-high coverage is generally the best way to stop defenses from putting it out there. It’s also something Mahomes would prefer never to see — through the first five weeks of this season against Cover-2, 2-Man, Cover-4, and Cover-6, per Sports Info Solutions, Mahomes had completed 38 of 61 passes for 522 yards, 349 air yards, one touchdown, four interceptions, and a passer rating of 67.8.
Against defined single-high coverage — Cover-1 and Cover-3 — Mahomes had completed 23 of 28 passes for 302 yards, 182 air yards, three touchdowns, no interceptions, and a passer rating of 147.3. No NFL quarterback had been more efficient than Mahomes against single-high coverage this season, so the Bills were going to ensure that he saw as little of it as possible. And when he did see it, he wasn’t going to like it.
Looking at the BUF coverage rates vs. Mahomes/KC.
• Cover 2 — 50.8%
• 2-Man — 23.8%
• Cover 1 — 9.5%
• Quarters — 6.3%Split-safety coverages…
— Matt Bowen (@MattBowen41) October 11, 2021
It was a naturally horrid matchup for Mahomes anyway, because through the first five weeks of the season in two-high coverage, the Bills had allowed 17 completions in 36 attempts for 166 yards, no touchdowns, four interceptions, two more dropped interceptions, and an opponent QBR of 21.1. To put that in perspective, the Chargers had allowed the second-lowest opponent QBR through the first five weeks at 56.6. Two weeks before, the Chargers kept Mahomes in check by playing far more man coverage than was usual for them; the Bills’ response was to stick with their script and execute at a high level.
Mahomes made this point after the game, when he was asked about miscommunications with his receivers.
“It’s just we’re seeing different defenses that we’ve seen in the past,” Mahomes said. “We have a lot of stuff, we read coverages and run routes to different spots and we’re just not on that same page. I have to trust in these guys that we’ll figure that out if that’s me knowing what they’re thinking and them knowing what I’m thinking and that’s what makes our offense so good. It’s something I don’t want to lose, it’s just about us practicing and going to work every single day and being on that same page.
“We recognize coverages as we run routes, That’s what has made us so good over the past few years. Teams can have the right coverage called, and we can run a routes a certain way. The guys are seeing coverages differently than I am. They’re different coverages — I don’t think anyone has faced coverages like we’ve faced over these last few games.”
That was Step 1 in stopping Mahomes. Step 2 was refusing to blitz him under any circumstances. On Sunday night, the Bills didn’t call a single blitz on any of Mahomes’ 63 dropbacks, but they still pressured him on 16 of those dropbacks and 12 passing attempts, sacking him twice.
Not that the Bills had been a heavy blitz defense before — they’ve brought extra defenders on just 16% of their defensive snaps this season, seventh-lowest in the league — but their decision to not blitz Mahomes at all was against type in a general sense, though certainly not in a specific sense.
The Bills did not blitz Patrick Mahomes on any of his 25 dropbacks in the first half.
The only other game in the NGS era where a defense did not blitz a single time?
The Bills in Week 6 of last season, also against the Chiefs (0 blitzes on 27 dropbacks).#BUFvsKC | #BillsMafia
— Next Gen Stats (@NextGenStats) October 11, 2021
As Next Gen Stats also points out, the Bills have blitzed Mahomes at a third the rate (10%) than they have blitzed all other quarterbacks (30%). There’s a reason for that — through his career, Mahomes has a passing EPA of +151, which leads the league over that period of time.
How did the Bills lock Mahomes up this time when they couldn’t before? From front to back, it was a not only a perfectly aligned performance, but also one the Chiefs did not expect from a schematic perspective.
