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Stopping the run in the 4-3 Defense

The Cleveland Browns have run a 3-4 in the recent past, but with new head coach Pat Shurmur and new defensive coordinator Dick Jauron coming to Cleveland, the smart money is that we'll run a 4-3.

The defense won't just look different, it will probably function a lot differently than those we've run recently. So how will we stop the running games of the Baltimore Ravens, Pittsburgh Steelers, and Cincinnati Bengals? It's all after the jump.


In reality, a 4-3 defense isn't that much different than a 3-4 defense because there is one less linebacker and one more defensive lineman on the field. It's the way the linemen are (usually) asked to play and what they (usually) do after the snap that constitutes the major differences between a 4-3 and a 3-4. For simplicity's sake, I'll refer to these things as "4-3 principles" and "3-4 principles", but keep in mind that there may be teams who line up one way and play with the other set of principles.

Simple = Quick

Linemen switching to a 3-4 defense will sometimes complain about having to "think too much" and not being allowed to "just play." 3-4 principles require linemen to read the play as it is happening and react to it. The 4-3, however, is predicated on turning linemen loose. In a 4-3, linemen each have one gap assignment; they are responsible for controlling the area between two blockers and tackling the ball carrier if he comes through their assigned gap.

Let's say that we are lining up in a "normal" 4-3 defense with a TE. The DL would be responsible for the weakside C gap, weakside A gap, strong side B gap, and strong side C gap:


It's just arithmatic

Utilizing normal "pro" personnel, the offense presents 7 gaps on the line which the defense must defend. That's perfect for the defense because 4DL + 3LB = 7 players to fill those gaps.


Things get tougher for the defense, however, when the fullback is introduced into the running play. The fullback presents an extra gap that the defense must account for--a gap that a skilled offensive coordinator can place anywhere along the line.


In order to successfully defend the run against 21 (2 RB, 1 TE) personnel, the defense must do one of two things:

  1. Cover two gaps with one player OR
  2. Bring another player up to cover a gap.

How the Browns will do this and in what situation will probably vary. For example: if you always bring a safety up in run support on 3rd and 4, that's a tendency other teams can scout and exploit. That's the sort of thing that coaches pull all-nighters to find out, and that sort of knowledge can make or break a key 3rd down play for your team.

Go with the flow

Below, I'll show how a 4-3 team would determine gap fits based on the flow of the backs. I'll show where a team could use a player to "two gap" or could bring a safety down to fill after the play is determined to be a run. There are three ways a two-back play could flow: flow strong (both backs to the tight end side), flow weak (both backs away from the TE), and split flow (one back each way)

Flow Strong


When the SAM backer reads flow strong, he will attempt to maintain outside leverage on the FB. He will get outside to the E gap that was just created by the FB, and he will "set the edge."

The MIKE will fill between the TE and FB in the D gap.

The WILL backer could either attack the A gap right away or be assigned both the front side A gap and the weak side B gap. If someone from the secondary is responsible for the cutback into the weak side B gap, the WILL backer can shoot the A gap and maybe make a TFL. This can also look like a blitz, which makes your defense's film harder to study.

Flow Weak


With the backs going away from the TE, the WILL backer will get outside the FB and set the edge, defending the D gap and turning runs back inside. If the FB blocks inside in the B gap, the WILL takes the gap just outside the FB.

The MIKE will go fast to the B gap. This is key because he will want to make the LG block him to prevent a double team with both the LG and C on the DT.

The SAM then becomes the player assigned two gaps; the backside A gap and the backside D gap. Obviously, a defensive back could be introduced to the run fit to eliminate the need for the SAM to two-gap.

Split Flow


If one back goes each way, the SAM and MIKE will key the RB. Between the two of them, they must cover the strong side D and strong side A gap if the RB continues away from the FB, or the weak side B gap and strong side A gap if he cuts back.

The WILL will key the FB and maintain outside leverage on him.

Play Fast

Notice how the gap assignments of the DL stay the same throughout each of these run fits. Every defensive lineman can fire off of the ball and get into his gap quickly. The reads for the LBs are mostly easy: key a back, then follow him a specific way into one of the gaps that is open. If done correctly, this should lead to a fast, attacking defense.