What is Cover 4? Quarters Coverage Explained

Cover 4, usually called Quarters, puts four defenders deep: both corners and both safeties each take a quarter of the deep field. Three defenders play underneath. On paper it looks like the safest pass defense you can call. In practice, many teams use it as an aggressive run defense too, because of how the safeties play.

The Structure

Before the snap, Cover 4 shows two high safeties, like Cover 2. At the snap:

• Corners take the outside quarters. They read the outside receiver (#1) and stay on top of him if he goes vertical.
• Safeties take the inside quarters. They read the inside receiver (#2) to their side.
• Underneath, three defenders, usually the linebackers, cover the hook and curl zones.

How the Safeties Read

The safety's read on the inside receiver is what makes Quarters work. Most teams teach a version of this:

• If #2 runs vertical, the safety takes him deep, which turns the coverage into man-to-man on that receiver.
• If #2 runs to the flat or stays short, the safety is free to help the corner on #1, usually by jumping an in-breaking route or doubling a deep one.
• If #2 blocks or the play is a run, the safety comes downhill and fills against the run.

That last read is why Quarters is also a run defense. The safeties start 8 to 10 yards deep, closer than in Cover 2, and they fit the run as soon as they read it. With both safeties involved, the defense can get nine players into the run fit.

Strengths

• Deep coverage. Four deep defenders against four verticals means every vertical route has a defender on it.
• Run support from the safeties. The safeties add two run defenders without giving up the two-high look.
• Disguise. It starts from the same two-high shell as Cover 2 and Cover 6, so the quarterback has to read it after the snap.

How Offenses Attack It

• Flats and quick throws. With only three underneath, quick outs, bubbles and swing routes to the flat often have nobody close to them.
• Corners left one-on-one. When #2 runs vertical and the safety takes him, the corner is alone on #1. Outside-breaking routes like the out and the comeback attack him without help.
• Play-action. Safeties who fill the run fast are vulnerable to a run fake with a receiver going behind them.
• Route combinations that stress the safety's read, such as a vertical by #2 paired with a post or dig by #1, which can put the safety between two receivers.

When to Call It

Quarters fits well on early downs against teams that run the ball and take play-action shots, because it defends both from the same call. It is weaker against spread teams that throw quick game to the flats, and it asks a lot of the corners, who often have no help.

See It In Action

The Cover 4 page in Spiral AI's Defense Library shows every defender's responsibility, and the library also has the common Quarters variants such as MOD. Use the Coverage Compare tool to put Cover 4 next to Cover 2.