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.[1]

Overview

In a usual three-level defense, there are three layers: the forcing unit (consisting mainly of linemen but possibly also including shooting linebackers and defensive backs), the underneath coverage (usually consisting of linebackers but possibly including other players, especially in the case of a zone blitz), and the contain unit (mostly defensive backs). 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 (as deep as 28 yards at the snap) 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.

gollark: 4703 somehow *does things* just because the law says it can, even though the law is just a human concept and only affects what humans do.
gollark: Really, one of the main things which makes (some) SCPs weird is that they take convenient abstractions/concepts and turn them into immutable physical laws, while our real universe just runs on... well, physics. 173 is affected by line of sight, even though this is just a thing humans do to reason about... looking at things. 005 is just a magic item which unlocks things, 048 is just a label we assign to things which somehow affects them.
gollark: Alternatively, the machine breaks, if it prefers simple changes - so I guess make it STUPIDLY redundant.
gollark: * didn't happen
gollark: Idea: what if you make a machine which will automatically open the box if an XK-class scenario occurs/is imminent?]

References


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