The Moron’s Guide to Football – Episode 2: Defensive Fronts

1. The Basics

As with the first article in this series, which covered offensive personnel groupings, defensive formations get their name from two of the most prominent positions on their respective side of the ball.

Again, there are 11 players on the field on defense (unless you’re up north in Canada, eh), and the number of linemen and linebackers are what lend their name to common defensive formations. The two most popular in gridiron football are 4-3 and 3-4 defenses. In a 4-3, there are 4 defensive linemen and 3 linebackers. In a 3-4, there are 3 defensive linemen and 4 linebackers. Unlike offensive personnel groupings, however, it is less common for teams to switch between 3-4 and 4-3 during a game, though certain plays and packages will deviate from the norm. This leads to most teams being described as either a 3-4 base defense or a 4-3 base defense as they operate primarily out of that formation.

Obviously, both 4+3 and 3+4 equal 7, leaving four players unaccounted for in each formation. In general, these four players are two cornerbacks and two safeties, though there are some exceptions (we’ll get into that in a Vikings-specific context in a minute). These 4 players are usually referred to as DBs or Defensive Backs.

Traditionally, the distinction was that defensive backs were responsible for covering receivers while linemen and linebackers were responsible for defending against the run and rushing the quarterback. As offenses continue to evolve – and as running backs and tight ends continue to become more and more involved in the passing game – linebackers are being increasingly expected to contribute in pass coverage.

So what’s the difference between a lineman and a linebacker? This may seem obvious, but linemen line-up on the line of scrimmage – most often in a 3-point stance (with their “hand in the dirt”) – while linebackers line up behind the linemen and are usually in a 2-point stance (hands off the ground, take a look at this for more detail on LB stances). This stance tends to make linebackers less predictable than linemen as it is not immediately clear whether they intend to rush the passer or drop back into coverage.

Oh, and here’s a useful tip: the easiest way to tell whether a team is in a 3-4 or a 4-3 defensive formation on a given play is whether the defense has a nose tackle (NT), indicated by a player lining up directly across from the offense’s centre (the guy snapping the ball).

2. The NFL Today

As I was putting this piece together, I asked TVG’s very own Northern Norman to guess how many teams in the NFL currently run a 3-4 defense. His guess? 7. My guess? 10 or fewer. The actual number? 14. This is according to ESPN, and is a lot more than I expected, but still fewer than the 18 teams that run a 4-3 base defense.

From the 1970s until fairly recently, the use of the 3-4 had been steadily declining to a point in the mid-1990s where only two or three teams were using a base 3-4 defense. In the 2000s and 2010s, however, more teams started going back to the 3-4 defensive formation. This mini-resurgence has likely been caused, at least in part, by the near constant success of the Pittsburgh Steelers, who have run a 3-4 scheme since 1985.

As alluded to above, the biggest distinction between a 3-4 and a 4-3 defensive formation is whether the defense has a nose tackle (NT) or two defensive tackles (DT). The reason this is so important is because it fundamentally alters the blocking and gap assignments for the defensive linemen.

In a 3-4 defense, the NT is usually responsible for both “A” gaps, meaning the spaces to both the left and the right of the center. The “gap” is the space between the players on the offensive line, and they are labelled based on their proximity to the centre (the A gaps are on either side of the centre, B gaps are to the outside of the guards and the C gaps are the space outside the tackles).

In his excellent The Art of Smart Football,1 Chris B. Brown writes that “great D isn’t the function of a magical scheme; it’s about mastering fundamentals and playing with discipline and effort.” While I agree with this in principle, and it’s an excellent coaching philosophy adhered to by many all-time greats (like Belichick over in New England), in order to effectively run a 3-4 defense, you also need the right players, both in terms of skill, but also as regards size and athleticism. Or, as Zimmer himself has put it, running a 3-4 defense “is always about personnel.” He went on to add that it’s not something you can do on the fly: “you have to commit to that before free agency and the draft.”

Without an effective interior lineman it doesn’t matter how much discipline and effort you play with, you’re going to get run over. Why? Because he is responsible for handling two gaps, the nose tackle (NT) needs to be a powerhouse. Without an effective NT who can dominate the opposing center it becomes almost impossible to effectively employ a 3-4 defense.

Likewise, the defensive ends (DE) in a 3-4 need to be able to eat up opposing double teams as they rush the passer and play run defense. There are very few players in the league with the skillset to properly allow a 3-4 defense to thrive, but when it works it creates numbers mismatches in favour of the defense (since one or more players are essentially covering multiple gaps). Notable players in 3-4 schemes that have the sort of size, length, and power to excel on the inside are game-wreckers like the Rams’ Aaron Donald, Pittsburgh’s Cameron Heyward and the Cheeseheads’ Kenny Clark. For players with the size, speed, and strength to excel on the outside of a 3-4 scheme think of guys like T.J. Watt, Von Miller, and Khalil Mack.

The 4-3 defensive formation, on the other hand, utilizes two defensive tackles (DT) instead of a single NT. In this formation, there are only three, rather than four, LBs behind the defensive linemen. As there are 2 DTs instead of a single NT, each DT is usually responsible for a single gap (rather than being required to cover both gaps). There are still two DEs in a base 4-3 defense, though their roles are slightly different. In a 4-3 defensive scheme, the DEs are much more likely to try and rush around the edge of the line to get to the opposing quarterback in the backfield, rather than always providing pressure or run stopping between the tackles.

The prototypical DE for a 4-3 scheme, which the Vikes have run for generations, is the legendary Jared Allen. DEs in 4-3 schemes tend to be slightly smaller and faster than in 3-4 schemes. For example, Allen was 6’6” and 255 lbs during his playing days (he’s probably still 6’6” but I have no clue what he weighs now), while J.J. Watt is 6’5” and about 300 lbs. Take a look at Allen’s historic 22 sack season and note how often he uses speed and lateral quickness to get around the outside of opposing tackles. Compare this with JJ Watt who is also a tremendous athlete, but more often uses power, strength, and swim moves to blow through the opposing offensive line and shed blocks rather than running around the edge (which he still does sometimes because the dude’s a genetic freak).

Fewer LBs are generally on the field in a 4-3 base defense, which means that they are more often tasked with stopping the run and pass coverage. As a result, where 3-4 teams look to their NT and DE’s to cause mayhem in the backfield and numbers mismatches (often opening up sack opportunities or big tackles for loss for the LBs), the 4-3 scheme relies on their front 4 to generate pressure. If a 4-3 team can effectively handle the opposing offensive line and get into the backfield with just 4 rushers, it opens up a multitude of possibilities for the defense as they can drop 7 players into coverage, instead of relying on LBs to generate pressure.

So which is the “better” defensive scheme? Like most things in football, it depends. Most coaches and players, myself included, would love to run a 3-4 scheme if they had the personnel, since it can create so many problems for the opposing offense. The legendary Fritz Shurmur agrees, writing that “although it is more difficult to execute most techniques from this position […] this alignment provides a great opportunity for the ends and nose tackle to unload, attack, or pressure the offensive linemen and drive them in a backward direction.”2 That being said, a 4-3 defensive scheme is more versatile and less likely to implode due to injury or individual players being outmatched by the opposing offensive line. It also, in my opinion, allows LBs who are effective in coverage to better utilize their skillset and confuse opposing QBs.

3. Skol!

As mentioned above, the Vikings are a long-time 4-3 defense. Bolstered by a fearsome front four, the 4-3 scheme has been a hallmark of the Vikings since the late 60s and early 70s when the Purple People Eaters were destroying the league and helping the Vikings make it to multiple Super Bowls, including three Super Bowl appearances in four years between 1973 and 1976 (don’t ask how they went). Alan Page, Carl Eller, Jim Marshall, and Gary Larsen – who actually preferred the nickname “The Purple Gang” – were famous for their motto: “Meet at the quarterback.”

The versatility afforded by a 4-3 defensive front is also a hallmark of Zimmer’s coaching. As mentioned in the first piece in this series, one of the reasons Zimmer loves 2 tight end offensive personnel groupings is the way that it hides the offense’s plan from the opposing defense. When the 2 TEs are also receiving threats it keeps the defense guessing as to whether it will be a run play or a passing play and whether the TEs will stay in to block or run routes. A similar concept applies in a 4-3 defensive scheme, where it is less clear what each of the LBs behind the front four intend to do on any given play.

Though the Vikings run a base 4-3 defense, they don’t necessarily have 3 LBs on each play. If the offense lines up with 3 or more receivers Zimmer tends to swap a LB for an additional CB. If an offense lines up in 11 personnel (1 RB, 1 TE, 3 WR) it is likely that the Vikes will respond by lining up in a 4-2-5 defense called a nickel package (because there are 5 defensive backs on the field rather than 4).

Other hallmarks of Mike Zimmer’s defense involve the corners playing press man coverage and lots of misdirection at the line of scrimmage. It is also vital that the defense can get pressure on the QB with just the front 4 rushers.

Zimmer’s signature defensive move, however, is the double-A-gap blitz. Zimmer loves to call variations of the double-A-gap blitz when he can push opposing offenses into third and long situations. Out of the nickel package Zimmer will have the 2 LBs line up on either side of the opposing center, causing a numbers mismatch on the line of scrimmage and forcing the center to make a difficult decision in terms of who to block. And, of course, just because both LBs line up in the A gaps doesn’t mean they’re both actually coming on the blitz. This element of uncertainty and indecision is a key part of Zimmer’s coaching philosophy overall. A few years ago the Minnesota Star Tribune ran a great breakdown of Zimmer’s double-A-gap blitz packages.

For an example of the type of misdirection Zimmer loves to throw at opposing quarterbacks, take a look at this insane interception from Eric Kendricks in the Cowboys game earlier this season. Not only does Kendricks drop into pass coverage, but at the start of the play he lines up like he’s going to rush Andy Dalton. He even takes a couple of steps forward at the start of the play before quickly fading back into coverage (after reading that the Dallas RB is going to stay in to block rather than taking the handoff or running a route). He keeps his eyes on Dalton the entire time, reading his eyes to see where he plans to go with the pass. Dalton doesn’t see Kendricks dropping back into coverage and throws it right where Kendricks knows he will. Most LBs in this position would probably have only been able to break the pass up, but because Kendricks is Kendricks he makes an insanely athletic play that not only leads to a pass break up, but to a highlight-reel interception.

Speaking of highlight reel interceptions, take a look at this INT from the very next week against the Panthers.

The Panthers are in 3rd and long, but Zimmer doesn’t dial up one of his patented double-A-gap blitzes. Instead, the LBs drop into coverage. The Vikings line up in what looks like a zone coverage scheme, but is a mix of zone and man. The DBs initially cover the quick passes in a man coverage look, but then most defenders drop into zones. This is because Zimmer knows that the Panthers are likely going to run crossing routes which set natural picks, so the defenders can “pass off” their player to another defender to avoid running into each other and leaving a player completely open for an easy touchdown. This sort of exotic hybrid coverage is a key feature of Zimmer’s 4-3 defense in Minnesota and it works perfectly here.

Initially, Kendricks covers a WR who runs into the end zone but he passes him off to the safety. Then, Kendricks picks up Robby Anderson, number 11 for the Panthers, while Eric Wilson picks up the RB out of the backfield (Mike Davis). Wilson gets beat on a nifty inside move by Davis, but Kendricks reads the play perfectly. Anderson is trying to set a “pick” or “rub” on Kendricks so that he can’t break up the pass to Davis. When Teddy sees that Davis beats Wilson with his cut inside, which is actually the right read, he expects the throw to be open so he goes for it. If Kendricks reads this wrong Robby Anderson comes across the formation into the flat where he’s wide open for an easy TD; but, of course, Kendricks isn’t wrong. He completely shrugs off Robby Anderson’s pick and jumps the route because he just wants the ball more, leading to his second highlight reel interception in two weeks.

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  1. Chris Brown does an excellent job breaking down NFL football in an easy to understand, yet sophisticated manner. The Art of Smart Football and The Essential Smart Football are highly recommended.
  2. Fritz Shurmer does a really nice job in his books. Those looking for a good overview of defensive football should read Shurmur’s Coaching Team Defense. People looking for an in-depth discussion of defensive line play – and therefore tons of discussion about 4-3 vs. 3-4 defenses – might turn to Shurmur’s Coaching The Defensive Line.