3-4 Defense

The 3-4 defense refers to three defensive linemen and four linebackers who comprise the heart of the defensive formation.

In the 70s, the 3-4 defense evolved to counter fast, powerful running backs. A nose tackle (or nose guard) lines up against the center. His job is to tie up two offensive linemen. Two defensive tackles flank him (they are sometimes called defensive ends, but they have to be bigger like true DTs). There is no middle linebacker. Instead, there are two interior linebackers and two outside linebackers. The OLBs essentially play two different positions in the defense. Sometimes they rush the QB as if they are DEs. Other times, they drop into coverage as LBs or line up off the line in order to pursue the rush and plug gaps. The three defensive lineman are tasked with occupying as many of the offensive linemen as possible to allow the four LBs to make the tackles. (By the 90s, very few teams used the 3-4. It received a resurgence in the early 21st century.) The 3-4 has a big impact in terms of zone blitzes. When identified by the QB, 4-3 zone blitzes are often exploited by quick slants. While a zone blitz from a 4-3 leaves an obvious zone undefended, a 3-4 zone blitz allows the extra linebacker to fill in the empty zone.