Double coverage
In gridiron football double coverage is a state of defensive playcalling wherein two defensive players are assigned to "cover" one offensive player. This situation is often seen with standout wide receivers and running backs.
It is extremely rare to have 2 defensive backs man-cover a single receiver. Commentators who use the term "double-coverage" almost always mean a cornerback covering a wide receiver man-to-man, with a safety playing "over the top" for deep ball assistance.
Double Coverage in Zone Coverage
Often double coverage can happen out of man coverage, but it can also be used out of zone coverage as well. Zone coverage is when linebackers and defensive backs cover a zone or big chunk of space on the field. Zone coverage is heavily used out of blitzes. It is important to understand that there are only five eligible wide receivers on the field at one time. On defense, there are either six or seven available defenders to cover these five wide receivers. One or two of these men can be used to drop underneath of a wide receiver's route while a safety or corner stays over top. The coverages in which this can occur are Cover 2, Cover 3, and Cover 4.
