If you’ve followed the snap counts each week, you’ve likely seen some details on how specific players are used on the team. With a little break from the action during the bye week, it felt like a good time to give some visual aids on the defensive side of the ball, where the team has started to establish an identity.

Concepts

Before we discuss trends and tendencies, I wanted to offer some visuals for a few of the defensive terms that are thrown out on a near weekly basis. A newer concept that’s crept into the Buffalo Bills’ defense this year is what I’ve been referring to as the “speed line.” For the speed line, a defensive tackle is replaced by a faster player like a linebacker or edge rusher. In the picture below, we have Star Lotulelei being replaced with Lorenzo Alexander. Remember Alexander, because he’s key to a lot of this.

Nominally, the Bills run a 4-3 defense, which is often called their “base.” As you’ll see in the charts below though, this is very misleading. The Bills are in a nickel defense far more often. This is simply when a team adds a fifth defensive back to the normal mix of two each. For this graphic, we have Taron Johnson circled as the fifth defensive back. If you see Johnson, the Bills are in nickel, as he’s their starting slot (nickel) corner.

The defensive package pictured below is best-suited for attacking on passing downs. All four linemen are fast and have some finesse to their game. The Bills count on at least one of these guys being able to win a one-on-one and get to the quarterback as fast as possible. The fifth defensive back is in place of a (generally) slower linebacker and is used to make sure receivers are covered, or to add another speed element to the pass rush if needed. As an aside, when both are healthy, Matt Milano and Tremaine Edmunds are in on every play.

To contrast the “speed line,” we’ll call this the “heavy line.” Strictly speaking though, this is an ordinary line in a 4-3, consisting of two defensive tackles and two defensive ends. The “heavy” helps emphasize that the Bills like to lean on this grouping when they think a running play is likely. Star Lotulelei is there to clog up most of the middle, and the combination of Trent Murphy, Kyle Williams and Jerry Hughes is versatile enough to cover all their bases.

To supplement the run game, the Bills might elect to go from nickel to “big nickel.” The only difference is that the fifth defensive back is typically a safety who is a little larger than a slot corner and/or better with the play in front of them. Below, Rafael Bush is the fifth defensive back for the Bills. Bush weighs around 10-15 pounds more than Johnson, which is a decent amount of extra momentum when attacking downhill. This unit is geared more to a passing play than the base, but with a little more insurance for a running down than the standard nickel.

The Bills can—and do—mix and match these concepts a good deal, which brings us to some nerdy tables with numbers and such.

Usage

Our first table looks at relative frequency on how these combinations are used. Above, we have 229 defensive snaps counted, which is a little more than a third of the playing time this season. For the method to this madness, the NFL compiles a list of defensive formations for each team. In the Bills’ case, they’ve had over 200 unique lineups this year already. For this project, any formation/lineup that has been used five or more times was classified according to the defensive line and defensive back concepts described above.

For the defensive line, the usual lineup with two defensive tackles (the heavy) is used about two-thirds of the time. The Bills elect to run with the speed package (Alexander instead of Lotulelei) about a third of the time.

It’s interesting that the speedier defensive line is never paired with the base defensive backs lineup. The base defense of three linebackers and four defensive backs for the Bills is often used when the offensive play call is harder to predict—this gives them some versatility.

Another takeaway is that the Bills love them some nickel. The base defense accounts for about 17% of the sample above. The Bills also lean very heavily on the normal version of nickel, with the big nickel looks being infrequent. When big nickel is used, it’s typically with the heavier defensive line on a predicted run play.

Perhaps the most important takeaway is the use of the speed line being used exclusively with nickel (with it rarely being big nickel). If the Bills read a pass, they sell out to stop it. This combination is a pretty aggressive answer to a predicted pass and quite vulnerable to a running play. Our last table of the day shows how well the Bills predict the offensive play call.

The combinations using the heavy defensive line show good situational awareness. The base defensive backs version is the most run-stopping-oriented setup on the table. From the sample, the Bills called this on actual run downs more than twice as often as not.

The big nickel with the heavy line should be reserved for more ambiguous downs, and we see a near perfect split.

Next, we have the heavy personnel up front with the faster backs in the cornerback version of the nickel. This defensive strategy for many teams would be one of their more pass- oriented configurations. The Bills have gotten it “right” by using it on passing downs almost two-thirds of the time.

Last but not least, the speed line should be reserved for obvious passing downs. The Bills have successfully identified a passing play and called on this concept a whopping 73 times out of 78.

Based on the sample data, Leslie Frazier is consistently selecting an optimal lineup based on the opponent’s play.

Data courtesy of the NFL.