Understanding NFL Football: The 4 - 3 and 3 - 4 Defenses

The two main defensive alignments used by all NFL (and college) teams are the 4-3 and the 3-4 defenses. The 4-3 defense has four down linemen and three linebackers while the 3-4 defense has the opposite, three down linemen with four linebackers. In both of these formations it is assumed that there are two cornerbacks and two safeties. As the names imply, these defensive alignments only refer to the numbers of linemen and linebackers and therefore do not refer to what kind of pass coverage a team may be in. Both defenses can use zones, man-to-man coverage or a mix of both as suits their own needs. While coaches like Bill Belichick of the England Patriots">New England Patriots will often try to confuse the offense by switching into more exotic alignments, the majority of all offensive snaps that take place in the league are facing one of these two main formations.

The 4-3 Defense

The 4-3 defense is the most prevalent defensive arrangement currently used in football. The four down linemen ("down linemen" refers to a player on the line of scrimmage who is starting from the 3-point stance, a crouch like position, leaning forward with one hand on the ground) take the responsibility of rushing the quarterback and stopping the run. Generally speaking, the defensive ends are quicker and take on a larger portion of the role of pressuring the quarterback, while the interior linemen (the defensive tackles) are generally larger men who are primarily responsible for stopping runs up the middle. However, all four of the linemen will work together and share both jobs. With four men on the line, ideally a team will not have to blitz to create pressure, leaving the three linebackers to assist in pass coverage and shutting down the running game as needed.

The 3-4 Defense