Alabama Football Terminology: Gap Sound Defense

The run up to the Cowboy Classic between the Michigan Wolverines and Alabama Crimson Tide has been examined from every angle, but sometimes terminology is used in breaking down the Xs and Os that the average fan might not get. One such phrase is “gap sound defense.” So, what is a gap, and how the defense play it soundly?

In the diagram below, the gaps are marked as A, B, C etc. It is the space that exists between offensive linemen and uses the center as the starting point. Above that are the defensive linemen locations. Alabama’s linemen, for reference, play the Zero technique, or Nose, and the Five technique defensive end position. Any NFL fan that is familiar with the Eagles “Wide 9” alignment can get an idea of how far the ends split out in Philadelphia from the diagram.

Defensive linemen are assigned responsibilities based upon gaps. A Zero technique nose tackle is almost always tasked with the A-gap. If the scheme has the nose tackle slanting either left or right on the snap, he can add the B-gap to his responsibilities. It depends on scheme. Five technique defensive ends play over the C-gap, and can inherit the B or D gap responsibility depending on how the defense is drawn up.

So how does a lineman play a gap sound game? It comes down to understanding what defensive linemen are supposed to do. The 3-4 makes defensive linemen generally play a two gap defense, whereas the 4-3 assigns single gap responsibility far more often. Ends in a 3-4 defense are as big as many 4-3 tackles, because the ends are expected to force an offensive line to employ two blockers on the single end. The 3-4 nose tackle has to occupy at least the center and one of the guards. Alabama’s Terrence Cody was even triple teamed at times. Offensive lines had to use the entire interior of their line to try and block Mount Cody. The ends and nose combine to keep the offensive linemen away from linebackers, so that the ‘backers can read and attack plays. The 4-3 ends and tackles are expected to make more plays as opposed to facilitate them, like their 3-4 counterparts.

The term “gap sound” means that the linemen are disciplined, and are able to nullify what the offensive line wants to do to them to open up holes along the defensive front. It is a very multifaceted assignment. The linemen have to maintain control of their assigned gaps, but they also have to keep contain.

Contain, another frequently used term, is exactly what it sounds like. Containment refers to keeping a quarterback stuck in the pocket without an escape route. Michigan quarterback Denard Robinson is most dangerous when he squirts out of a hole that opened up as the pocket begins to collapse. The simplest fix for that problem is to keep those holes to a minimum by maintaining assigned gaps. If the end is able to consistently beat a single block, that end has to be careful about his angle of attack against Robinson. A poor angle means a missed tackle, lost containment, and a footrace to catch Denard.

“Gap sound” is just one example of terminology that can throw fans for a loop. Have another term you want don’t understand and would like to have it explained? Leave a comment, or a tweet, and we’ll do more of these.

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