Buffalo Bills 2021 Team Study

Part 2 of my 32-part series breaking down every team’s performance in 2021. Check out part 1 here: New England Patriots. Part 3 is now available here: New York Jets.


Eff. RatingAdj. RatingRank
Offensive Eff. Rating (blue and red) v. opponent average allowed (grey).
Pass EPARush EPAAdj. Pass Rate

The Bills offense was elite again in 2021. They did just about everything well and succeeded in almost all situations. Josh Allen led a versatile and dangerous passing attack that was complemented by an improved ground game. They could press the lead when ahead and they proved they could mount a comeback against a strong defense when they erased a 21-point deficit to force overtime against Tampa Bay. They played their best football in the biggest spots, scoring at least 27 points against every playoff team they faced (other than the bad weather game against New England), including 83 points in two playoff games.

Their only real struggle involved inconsistency completing passes. Their 36 drops ranked 2nd-highest in the NFL, up from 27 drops in 2020. And Josh Allen’s on-target percentage fell to 75% after a strong 78.4% in 2020, despite a lower average depth of target (8.2 yards from 8.6 yards in 2020). Many analysts called for regression by Allen this year and I suppose that’s what regression looks like. Still, drops are generally fluky in the NFL and Allen’s inaccurate passes looked more like random mistakes than true problems with his mechanics or decision-making. As noted above, he played his best games in the biggest spots and might have taken some inferior opponents too lightly. That’s an easy problem to fix.  

Arguably no quarterback matches Allen’s unique blend of elusiveness and toughness. He gave up a sack on only 19.3% of quarterback pressures, lowest in the NFL. His ability to turn pressures into positive plays separates him into the highest tier of quarterbacks because he can turn negative plays into positive plays. This translates to greater relative success when more is put on his plate. The Bills played their best offensive football against the toughest defenses, including the top pass defenses. Chart A tracks the Bills’ relative offensive effectiveness against each opponent ranked by its overall pass defense EPA/play on the season.

Chart A

Chart A: Adjusted Eff. Rating by opponent pass defense in EPA/play.
*Omitted Week 12 v. NE due to significant weather impact on offense.

Their three best offensive performances on the season came against the Saints (+1.35 Adj. Rating) and Patriots (+1.49 and +3.89), who were the 3rd and 4th best defenses versus the pass. As noted above, their mistakes were usually their own. Drops and inaccurate passes tend to be opponent-agnostic. If anything, they played their best football when most focused. They utilized a variety of weapons in the passing game, getting at least 540 yards from five different receivers. And particularly once they started featuring Devin Singletary, they ran the ball effectively on both handoffs and designed runs for Allen. Trying to stop the Bills offense was like playing whack-a-mole; if you managed to shut down one option they just found another way. This made them particularly dangerous in the playoffs when the stakes were highest.

Of course, like any offense, they suffered a setback when they were not at full strength on the offensive line. They had a stretch of games in the middle of the season where they were banged up, most importantly against Jacksonville. Playing without Joe Feliciano, Spencer Brown, and Dawson Knox, they unsurprisingly played their worst offensive game of the season in a mystifying 9-6 loss. Once they were back to full strength on the offensive line they hit their stride again.

It’s fair to wonder about the impact Brian Daboll’s departure will have on this offense. We have only seen Allen excel under Daboll. But they stayed in house, promoting Ken Dorsey the quarterbacks coach. This signals an intent to opt for as much consistency as possible. They have also used a plethora of unique weapons in the passing game for two years now, so they will need to retain that depth to maintain their elite performance. But the betting markets believe in this team, installing them as early favorites to win the Super Bowl. The hype is justified. Based on their overall performance in 2021, they deserve it.


Eff. RatingAdj. RatingRank
Defensive Eff. Rating (blue and red) v. opponent average allowed (grey).
Pass EPARush EPABlitz RatePressure Rate

The Bills defense wreaked havoc on opposing quarterbacks all year. They led the league in pressure rate, net yards per pass allowed, completion percentage allowed, third and fourth down conversion rate allowed, and overall defensive pass EPA/play. They rotated down linemen to keep them fresh. On the season, ten different Bills defensive linemen played over 200 snaps. They did not rely on a single disruptor and instead rotated their deep talent to keep them hungry and active. This platoon approach meant no player had more than seven sacks and only Mario Addison had more than four.

They also kept quarterbacks uncomfortable with excellent coverage. Even playing without star cornerback Tre White for the second half of the season, the Bills secondary (and coverage linebackers) played at a consistently high level. But the Bills weren’t tested much by mobile quarterbacks. They didn’t face a true dual-threat quarterback all year, and in the playoffs when Mahomes started using his legs most, they got burned. Granted, they also did not have Tre White in that game. But defenses built to exert constant pressure thrive against immobile quarterbacks, so the schedule played out perfectly for them.

It’s fair to question how well they would have performed against true mobile quarterbacks because their defense excelled so much when harassing quarterbacks in the pocket. But they did well in 2020 against Lamar Jackson, Kyler Murray, and Russell Wilson because they were more vulnerable to power than speed. This held true in 2021, as they struggled relatively against teams that ran the ball well. Chart B shows the Bills’ relative defensive effectiveness against their opponents ranked by overall rushing EPA/play on the season.

Chart B

Chart B: Adjusted Eff. Rating by opponent rushing offense in EPA/play.

Their worst defensive performance came against Jonathan Taylor and the league-leading rushing attack of Indianapolis (-1.26), and they played their best games against teams that could not run the ball effectively, like HOU (+1.90), NYJ (+1.26), MIA (+1.23), and NO (+1.10). However, betting NFL games is about understanding perception versus reality. Everybody knew the Bills were vulnerable to the run, and it was arguably overstated. Two breakaway runs – one by Harris and one by Henry – skewed the data. Without those two runs, they allowed the 5th-fewest yards per carry on the season. Obviously those runs happened, so they don’t get a pass. But two plays in an entire season doesn’t represent a repeatable pattern.

It’s correct that the Bills were more vulnerable on the ground than through the air. But they were not a soft defense that a good offensive line could routinely punish. When this became the narrative, there was actually value fading this overreaction. This created betting opportunities in the two rematches against New England – who were supposedly going to be able to bully them on the ground – for those paying attention.

Moving forward, the Bills should be optimistic they have a strong defense built to stop the pass. That’s how you win playoff games in the NFL. They also are not reliant on a single stud, although getting White back will be huge. This makes them more likely to repeat their success. If so, they’ll likely have to overcome a tougher schedule and show they can win on defense against the best offenses. I would expect some minor regression overall given their 2021 schedule, but they still should be a strong unit.

Key Takeaways

When to bet on the Bills: I’m looking to find any reason I can to back the Bills. Uncharacteristic (and non-predictive) results can dampen enthusiasm on a team that is the best and most complete team in the NFL. Variance happens in the NFL, so look to find value against the strongest competition after they suffer a bad-looking loss due to non-predictive elements (such as the weather game against NE or their loss to IND where they simply didn’t touch the ball enough).

When to fade the Bills: Unless they regress in 2021, betting against the Bills is probably not a profitable tactic. However, try to avoid betting on the Bills to cover a big spread against teams that project to run the ball well. This not only reduces possessions (making it tougher to cover) but also plays into the Bills’ defensive weakness.

What to look for in the offseason: I’m particularly interested in how they approach the offensive side of the ball with a new offensive co-ordinator and a potentially different set of weapons. Tre White’s recovery from an ACL injury will also be something to watch, as he may not be full strength right away. I want to hold Bills futures because, absent major injury issues, they will almost certainly be well-positioned for another playoff run.

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