Football 101: The "4-3" Defense

With football season approaching us, it is important that you understand some of the more reiterated parts of the game. So today's look into the strategy of the game within in the game is a detailed analysis of the 4-3 defense.

The 4-3 defense, sometimes simply referred to as the "43" defense, consist of 4 defensive linemen, 3 linebackers and 4 defensive backs. The 4 defensive linemen generally consist of 2 defensive ends and 2 defensive tackles. The linebackers are made up of 2 outside linebackers and 1 middle linebacker. And the defensive backs are usually comprised of 2 cornerbacks and 2 safeties.

Generally, in a 4-3 defense, the defense has the defensive linemen take control of one gap. For the defensive ends, they usually are responsible for the C gap, which is immediately outside the offensive tackles. The defensive tackles are either responsible for the B gap, between the guard and the tackle, and the A gap, between the center and the guard, with each tackle taking one gap or the other on opposite sides of the center. So in one example of a base 4-3 defense, you would have the left end in the left C gap, the left defensive tackle in the left B gap, the right defensive tackle in the right A gap, and the right defensive end in the right C gap. Again, in most 4-3 defensive schemes, the linemen are responsible for one gap, thus each linemen penetrates their corresponding gap, making sure no one runs through it or uses that gap as their path to the quarterback.

The linebackers, in turn, are also responsible for gaps, but generally, most linebackers have more than one gap to account for before the snap, because linebackers are off the line of scrimmage (by about 4-5 yards), thus they have more time to react to the direction of the play. So on the occasion that the offense runs the ball, most linebackers have 2 gaps to choose from, when it comes to pursuing or containing the run, depending on what direction the ball carrier goes.

The middle linebacker, for example, could have the A gap on a play up the middle, however, if the play goes to the right side of the defense, that middle linebacker may have an alley-a newly created gap-to fill while in pursuit of the run. Usually, at least one of the outside linebackers is responsible for contain, where they are responsible for getting as wide as the widest player out of the backfield. However, sometimes that responsibility can be passed off to a safety.

When it comes to the run, generally, not more than one defensive back has primary run responsibility in a 4-3 defense against a typical pro offensive set. If a defensive back is called on to help with the run, it is usually one of the safeties, who acts as a contain player or as an alley filler. Generally, at least one safety is left without any run responsibility and is left to pick up whatever gets through the front 7 or 8 men in the box (see my article on "The Box"). Cornerbacks are almost never incorporated into the run defense unless there is less than 2 wideouts, or if a particular zone or blitz coverage ask them to get involved with the run.

There you have it. Those are the general responsibilities of the 4-3. Typically, you will see the 4-3 employed on 1^st downs, as it is a favorable defense against the run. Also, most teams aim to have their best 11 players combine to make this formation, which is why most starting lineups are listed out of the 4-3 formation. At the pro level, you will rarely see a standard 4-3 employed on 3^rd down, as most defensive coordinators have a specific objective on 3^rd down, and the 4-3 is more of a general defensive lineup.

Lastly, you didn't hear me discuss pass defense a whole lot in this piece, mainly because there are a multitude of different responsibilities that can be assigned to almost any defensive player when it comes to defending the pass, so there's really no need to look at pass defense from a formation-specific perspective.