Sky, Buzz and Cloud: Cover 3 Named by Who Takes the Flat

Every Cover 3 call has the same deep structure: three defenders split the deep field into thirds, and four defenders play underneath. What changes from call to call is who covers the flat on the strong side, and that one decision moves three or four other players.

The easiest way to keep the calls straight is to name each one by the player who takes the flat:

• Sky = safety
• Buzz = backer
• Cloud = corner

Once you know who has the flat, everyone else's job follows from it.

Sky: the Safety Takes the Flat

In Sky, the strong safety rolls down from his pre-snap depth to the strong flat. The free safety takes the deep middle, and both corners bail to their deep outside thirds. Underneath, the linebackers play the two hook zones and the weak curl/flat.

The safety in the flat is the force player against outside runs. He sets the edge and turns the ball back inside. Against the pass, he walls the inside receiver off the curl and then gets to the flat.

What it gives you: a fast, physical defender at the edge against the run and against quick throws to the strong side.

What it costs: the safety is now playing a short zone, so the hook defenders inside him are linebackers, and crossers and tight-end seams run past linebackers instead of a safety.

Buzz: a Backer Takes the Flat

In Buzz, a linebacker (usually the SAM, or the nickel in sub packages) expands to the strong flat. The strong safety still comes down at the snap, but he drops into the strong hook/curl zone inside the linebacker instead of going to the flat. The name describes the safety's drop; the easy way to remember the call is that a backer has the flat.

The deep thirds don't change. Both corners and the free safety play exactly what they play in Sky.

What it gives you: a safety sitting in the underneath middle, where he can wall the seam and break on crossers and curls. Against teams that like to throw over the middle to the tight end, that is a better matchup than a linebacker.

What it costs: a linebacker is now the flat defender and the force player on outside runs, so quick throws to the flat and outside runs to the strong side are tested against a slower player.

Cloud: the Corner Takes the Flat

In Cloud, the corner squats in the flat instead of bailing to the deep third. Because the corner is no longer deep, the safety rotates over the top to take that deep outside third. The other corner plays his deep third as usual, and the free safety stays in the deep middle.

The cloud corner usually aligns close to the line, gets a hand on the outside receiver, and then sits in the flat. If the inside receiver goes to the flat, the corner is right there.

What it gives you: a corner sitting on top of quick outs, bubble screens and swing routes, and a jam on the outside receiver.

What it costs: the safety rotating to the deep third has a long way to travel, so a fast outside receiver running a go or a corner route tests whether the safety gets there in time. Cloud is usually played to one side at a time.

Side by Side

• Sky: strong safety in the flat, linebackers in the hooks, corners and free safety deep.
• Buzz: linebacker in the flat, strong safety in the strong hook/curl, corners and free safety deep.
• Cloud: corner in the flat, strong safety in the deep outside third, other corner and free safety deep.

Defenses often play more than one of these in the same game, and some combine them, such as Cloud to one side and Buzz to the other (Cover 3 Mable). Because all three can start from the same two-high look before the snap, the offense often does not know which one it is facing until the ball is snapped.

Study Them

Spiral AI's Defense Library has every variant drawn with each defender's responsibility: Sky, Buzz, Cloud and Mable. The coverage variants flashcard deck drills the differences.