An In-Depth Look at the 4-3 Defense

This is an analysis of the 4-3 defense used in American football. The 4-3 defense is thus called because there are four defensive linemen and three linebackers in the front seven positions of the defense. The 4-3 is designed to get more pressure from the line of scrimmage from the defensive lineman and usually relies less on blitzing.

As you can see here the 4-3 defense was probably invented by Tom Landry who eventually called his version the flex defense. The 4-3 defense uses two defensive ends and two defensive tackles as opposed to linemen used in the 3-4 defense as you can read about here.

The defensive ends line up across from the offensive tackles, and the defensive tackles across from the offensive guards. The ends will usually line up to the outside shoulder of the offensive tackles. Their job is to get to the quarterback on passing plays and to contain the outside on running plays while trying to make a tackle. The defensive tackles in the 4-3 defense try to occupy blockers to keep them off the linebackers, while also trying to pressure the middle of the offense.

The three linebackers are the middle linebacker, strong side outside linebacker and the weak side outside linebacker. The strong side linebacker lines up on the side of the field where the tight end is playing for the offense, if there is one in the formation. The strong side linebacker will usually cover the tight end or a running back on passing plays but sometimes blitzes. The middle linebacker mostly plays run defense first but will also play zone pass defense. The weak side linebackers blitz more than the other linebackers in the 4-3 defense and also cover backs out of the backfield on pass plays.

The defensive backs in the 4-3 defense are two cornerbacks and two safeties. They line up in different places depending on their coverage assignments. The safeties tend to do safety blitzes less than in a 3-4 defense due to less people being back in pass coverage.

Some famous versions of the 4-3 defense or well known teams that used a variation are as follows. The Pittsburgh Steelers "Steel Curtain" defense was a 4-3 with such notables as "Mean" Joe Greene, Ernie Holmes, Jack Lambert and Jack Ham playing their roles. Dallas's "Doomsday" Defense under Tom Landry was the 4-3 "Flex" as mentioned above. The "Cover 2" defense or "Tampa 2" is a 4-3 defense. Buddy Ryan's "46 defense" was a variation of the 4-3.

Sources

Football.calsi.com looks at the 4-3 defense

Letstalkdefens.com article on the 4-3