Michigan Wolverines: The 4-3 Defenses — Part II
The linebackers have gap responsibilities for areas called bubbles that are unattended weak spots not covered by the four interior linemen. The basic 4-3 Over defense has three such holes versus only two with the base 4-3 Under. In the 4-3 Over, the weakside backer has the B gap, naturally on the weak side between the guard and tackle. The middle linebacker is pretty much head up over the center and somewhat protected by the defensive tackles playing over the center. He has the strongside A gap bubble. The strongside Sam linebacker’s bubble responsibility is the strongside C gap.The 4-3 Over defense must have a true tough linebacker type in the middle. Spread and option teams can present a problem with the dive or reads that attack the middle of the line. If the defensive tackle over the center is adequate, a very strong middle linebacker can be very successful in stopping the inside running game. If either the nose tackle (0,1) or the strong side (3) technique tackle demands a double team by the offensive line, the middle linebacker becomes even more dangerous. In the 4-3 Under alignment the nose tackle better deal with a double team and the middle linebacker better be very good at avoiding or shedding a second level block, or the result will be easy yards between the guards.
The weakside or Will linebacker in many systems is a tough, bulked up safety type. The Will needs to cover the slot or be replaced by a nickel substitution, which likely is another safety type- just more mobile and faster.
The 4-3 Over helps plug the middle, an area that has been gashed at times the last two years by even the least of Michigan’s opponents. The 4-3 Over helps with the spread and read option if the interior defensive linemen get upfield and funnel the runner out of his hole to the outside. The two outside linebackers may be able to get away with some deficiencies, but both must have adequate speed and be very sound tacklers.In contrast, when playing teams that use the I formation for iso and blast plays in the bubble areas, and two tight ends, the 4-3 Under is a normal choice. As mentioned, it is easy to shift from an under to an over set. Teams that use two backs and have success in the power game, love seeing the 3 holes, or bubbles, of the 4-3 Over versus the two bubbles of the 4-3 Under. Teams love to run power between the 3-technique tackle and the 9 technique defensive end on the strong side. Here comes the blast and isolation, plus a fullback looking to kick out a defender. As a result 4-3 Over defenses frequently either rely on one or two great players to blow up that package, or more likely make alignment adjustments.
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Written by GBMWolverine Staff — Doc4Blu
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