4-4 defense

In American football, the 4–4 defense is a defensive alignment consisting of four down linemen and four linebackers.

Originally seen as a passing defense against the spread, modern versions of the 4-4 are attacking defenses stocked with multiple blitz packages that can easily be concealed and altered. The modern defense is based on speed, athleticism and intelligence rather than on size and strength. Versatility is key because players may have to change roles from one play to the next. A top priority of the 4–4 defense is stopping the run by keeping eight men close to the line of scrimmage. This also makes it difficult for the offense to identify where the pressure comes from when the defense blitzes.

Four man fronts are seen in the 1940s as ad hoc ways to deal with the "Bears" T, as the result of two linemen dropping off from the 6-2 of the time into short zones, and later as a prepared defense for use against the spread offenses of the time. In the 1950s, the six man line was no longer seen in the pros as a base defense, and the wide tackle six evolved to handle the interior attack of the Power T, and the outside threats of the Split T. To deal with flankers and split ends, contain theories such as the "five spoke" contain were developed, where the defensive ends became much like outside linebackers and had pass defense responsibilities. Homer Smith, in his history of 8 man lines, shows formations starting with the 1940s style 6-2, changing into the wide tackle six, and eventually, six man lines becoming 4 man lines as the defensive ends were relabeled outside linebackers. This change is similar to the defensive ends of the 5-2 being relabeled the outside linebackers of the 3-4.

Requirements for defensive tackles are highly dependent on the version of the defense being played. For example, the 4-4 of Joe Roman requires quickness, size, and a player no taller than 6' 4". In the 4-4 Split of Roman, the defensive tackles line up heads up on the offensive guard, or perhaps on their outside shoulder. In the 'G front' of Frank Beamer's teams, the weak side tackle lines up on the inside shoulder of the offensive guard, and the strong side tackle lines up on the outside shoulder of the offensive guard.

Requirements for defensive ends are highly dependent on the version of the defense being played. Speed and height are often valued, and defensive ends in these systems are often converted linebackers. Though alignment is highly dependent on the front, weak side ends are often outside the offensive tackle, and strong side ends outside the shoulder of the tight end. In the 'G front' of Virginia Tech, the Sam linebacker and the end switch positions, with the end assuming a position just inside the shoulder of the tight end, and the Sam linebacker staying wide of the end, along the line.

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