TSN:Why is the 3-4 defense back in vogue?
For years, the Steelers were one of the few teams -- if not the only team -- consistently using the 3-4. Now, they are one of five, along with the Falcons, Ravens, Texans and Patriots. Several other teams use a three-man front in specific situations.
One reason for the trend is because a true 4-3 defensive end is the toughest position to fill. The pass-rushing ends coming out of college are undersized, so many teams move a college end to the rush linebacker position, which is what the Ravens are doing with Terrell Suggs. In this spot, Suggs can spend most of his time in upfield pursuit and avoid physical battles with heftier and stronger offensive tackles.
Against the run, the 3-4 scheme uses three big, two-gap defensive linemen playing nose tackle and the two end positions. These linemen are asked to occupy blockers up front, forcing the outside linebackers to seal off the edges. This leaves two inside linebackers chasing down the run instead of one, which helps explain why smaller 4-3 middle linebackers Zach Thomas of the Dolphins and London Fletcher of the Bills wear down during the season.
Against the pass, the 3-4 scheme gives a defense coordinator more options. The Steelers have the ideal situation with two versatile outside linebackers -- Jason Gildon and Joey Porter. Either player can drop into coverage or rush the passer.