Mike Tanier

In football, confusion favors the defense.

If you need evidence, watch the fourth quarter of a preseason game. When the rookies and roster fodder are on the field, the disorganized offense rarely gets anything done. The defense is disorganized too, but they can make basic calls, win one-on-one matchups, be athletes, and wait for the offense to trip over its own feet. Simplified football is usually low-scoring football, and defenses can still be effective when coaches just tell players to “go get ‘em.”

A few weeks ago,I wrote about how the lockout will hurt complex offenses by reducing preparation time. It will hurt complex defenses too, though not nearly as much. We can still use the Football Outsiders Game Charting Data to determine which defenses will have to scale back the most in the event of a shortened training camp. A fudge ripple defense full of tricky blitzes is bound to be less dangerous when it starts scooping vanilla calls.

The blitz is in
It’s harder to determine defensive calls than offensive plays from the television tape. We all know what a screen pass looks like, but can you tell a Cover-2 from a Cover-3 zone? Some judgments are impossible without asking the coaches themselves. The Football Outsiders game charters make as few subjective calls as possible, so we will be basing defensive “complexity” on a few easy-to-spot strategies.

Zone blitzes: In a zone blitz, a defensive lineman drops into short zone coverage while linebackers or defensive backs blitz from a different angle. Zone blitzes require precise timing, and linemen need extra practice to perfect their coverage techniques. If the lockout erases a week or two of camp, zone blitz packages may get short shrift.

Some teams rely on the zone blitz far more than others. The Ravens zone blitzed on 12.4 percent of pass plays. The Texans zone blitzed just 11 times all season, or 2.4 percent of pass plays, the Chiefs just 17 times on 3.4 percent of pass plays. The Texans have a new defensive coordinator, so leave them aside; the lockout is more likely to affect the Ravens than the Chiefs when blitzing.

Pass rush variety: There’s nothing complicated about a standard blitz: send your fastest, angriest linebacker after the quarterback, then enjoy the carnage. So a team that blitzes a lot does not necessarily have a complex defense.

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But what about different kinds of blitzes? Some teams send five defenders, some six. Some switch tactics and rush just three defenders, with the other eight in pass coverage. A few teams mix-and-match all of these tactics: one minute they are rushing three, the next they are blitzing seven. A defense with that much variety must be difficult to learn and install.

Take the Jets, a team known for unpredictability on defense. They rushed six or more defenders on 14 percent of pass plays last year. They also rushed just three defenders 13 percent of the time, and they tried everything in between. By contrast, the Lions rushed six or more defenders just 6 percent of the time, and they rushed three just six times the entire year, most of them Hail Mary-type situations. It’s safe to assume that the Jets have a more complex scheme than the Lions.

We can turn all those percentages into one number that describes pass rush variety using standard deviation. (No, wait, don’t click away!)

Standard deviation measures how “spread out” a set of numbers is. The Lions’ pass rush percentages are all spread out, going from 1 percent (for three-man rushes) to 76 percent (for four-man rushes). The Jets’ percentages are more closely bunched. The lower the standard deviation, the more regularly the defense does different things, making that defense more complex. Standard deviation isn’t meant to be used like this, but it gets the job done for a quick-and-dirty study.

The Lions’ standard deviation was 29. The Jets’ was 12. We can combine those figures with the zone blitz data to create a Simplicity Score. We just have to jiggle the numbers, because more zone blitzing makes a defense more complicated, not less. So let’s take each team’s zone blitz percentage and subtract it from 15 percent to make higher numbers equal simpler systems. That’s the last bit of math, I promise. We now have a Simplicity Score for defense.