3-4

3-4

The 3-4 defensive set consists of 3 linemen, 4 linebackers, and 4 defensive backs. Teams with several dominant linemen to go along with fast, athletic linebackers typically find success with this formation. With less bulk up front, the linebackers play a key role in this set.
4-3

4-3

The 4-3 defensive set consists of 4 linemen, 3 linebackers, and 4 defensive backs. Slightly better against the run than the 3-4 with the added lineman, this set is slightly weaker over the middle and on the edges.
4-4

4-4

The 4-4 defensive set consists of 4 linemen, 4 linebackers, and 3 defensive backs. With up to eight men in the box, this set is hard on the running game and short passes. If the quarterback has time to throw, he can exploit this defense with some deep passes.
5-2

5-2

The 5-2 defensive set consists of 5 linemen, 2 linebackers, and 4 defensive backs. Running between the tackles is hard work agains this defense, but short to mid-ranges passes across the middle become a lot easier.
Nickel

Nickel

A Nickel defense consists of 3 linemen, 3 linebackers, and 5 defensive backs. Fairly soft against the run, the nickel defense is hard to throw against with five defensive backs leaving little room for the receivers to get open.
Dime

Dime

A Dime defense consists of 3 linemen, 2 linebackers, and 6 defensive backs. Extremely difficult to pass against, but extremely easy to run against. This defense is playing the pass all the way.