Understanding the Cover 3 Zone Defense in Football

The three defensive backs help protect against long passes

Cover 3 Defense
Andrew St. Clair

The cover 3 zone is a standard defensive scheme for the secondary and linebackers in all levels of football, from youth teams to the National Football League. As the name implies, the cover 3 zone deploys three deep defensive backs to cover their respective thirds of the field (see figure).

The basic philosophy behind the cover 3 zone is to provide a good balance of run and pass defense. By providing more deep defenders than the cover 2 zone, this defensive scheme makes it more difficult for teams that focus on long passes to come up with big plays down the field.

Positions in the Cover 3 Zone

The three deep zones in the cover 3 are most often covered by the two cornerbacks (left and right thirds of the field) and the free safety (middle third), called "free" because he usually roams the defensive backfield and is the last line of defense.

The strong safety, so named because he plays on the side of the line of scrimmage that has an extra lineman, has curl/flat responsibility on the strong side, meaning pass routes up to 10 yards past the line of scrimmage and out to the sideline (the "flat"). The "Will," or weak side, linebacker, has responsibility for the same zone on the weak side.

Strengths of the Cover 3 Zone

This scheme has great strengths, including a balanced defensive philosophy against the run and pass. There are three deep defenders, which means less ground for them to cover compared to a cover 2. If the defensive line is strong and the players are disciplined, a team can make the cover 3 zone a standard tool in the defensive toolbox.

Weaknesses of the Cover 3 Zone

The defense in cover 3 becomes a little vulnerable to short passing routes because the cornerbacks are bailing out of their usual positions to play deep in their zones. While cover 3 provides a good balance between the run and the pass, it is not particularly strong in either area.

Good offensive teams will be able to recognize the cover 3 and change the play at the line of scrimmage, or "call an audible," to capitalize on these weaknesses. If the defense is facing a strong running team, the cover 3 will be less than ideal unless it has great strength in the trenches, the common term for the defensive line positions.

For a well balanced defensive team, the cover 3 is a solid scheme that can work against the run and the pass.

The Cover 2 Zone

By comparison, the cover 2 employs the two safeties in deep coverage, each taking half the area, while the cornerbacks and outside linebackers cover the short pass routes in the flats. The "Mike," or middle, linebacker is responsible for passes in the middle of the field.

The cover 2 zone works well against the run and short passes, but it leaves the safeties with a lot of ground to cover, exposing them to deep pass threats.