Two-level defense


In American football, a two-level defense is a defensive formation with only two layers of defense instead of the customary three layers.

Overview

In a usual three-level defense, there are three layers: the forcing unit, the underneath coverage, and the contain unit. A two-level defense does away with the contain unit in favor of increased pressure on the offense. Two-level defenses will often use one deep safety to enforce an end line on the offense, but the Bear 4-6 is a two level defense with contain handled solely by the single coverage skills of the cornerbacks. The "Bear" can also function as a three-level defense, and indeed concealment of the defensive structure is a key to making this defense work.
The two-level was invented to combat the run and shoot offense in the 1980s, but has stayed in use due to its adaptability in combating all types of offenses. The defense of spread formations remains a strong suit of this model.