Cover 3 Defense: Three Deep Thirds and Four Underneath

Cover 3 at a glance

Coverage type

Zone

Deep defenders

3

Underneath zones

4

Rushers in this call

4

The Play Designer's base version of the call. Teams adjust who rushes and who drops every week.

Who drops where in this call

In the call drawn above, the corners drop to the outside thirds and the free safety takes the deep middle third. Underneath, the strong safety rolls down to the right flat, the Will linebacker takes the left flat, and the Sam and Mike linebackers drop to the hook/curl zones inside them.

That is the classic version former NFL safety Matt Bowen teaches in his National Football Post install: at the snap the strong safety comes down into the box, the free safety rolls to the deep middle, and the strong safety and Will both take a curl-to-flat drop. Bowen describes that drop as going at a 45 degree angle to 10 to 12 yards, holding off the curl, then driving to the flat when the ball is thrown. Depths like that vary by coach and system.

Sky, Cloud and Buzz: one shell, different rotations

Cover 3 is a family, not one play. Glazier clinic notes from Susquehanna defensive coordinator Pat Ruley list 3 Cloud, 3 Sky and 3 Buzz as separate calls, each picked for a different offensive problem.

NFL.com analyst Bucky Brooks describes Seattle's Buzz: one safety stays in the middle of the field while the other drops as a curl-flat player or into the hook zone. Bowen, writing for Bleacher Report, adds that when the safety takes the middle hook in Buzz, a linebacker bumps out to the curl-flat. In his Cloud example, one cornerback jams the outside receiver and then sinks under a possible corner route while the strong safety rolls back to the deep outside third. The deep structure stays three deep; what changes is who comes down and who goes back.

Why coaches trust it against the run

The safety who drops into the box is the key. The Scouting Academy's Inside the Pylon glossary says that safety helps guard against the run, and Bowen calls the eight man front the reason Cover 3 shows up so often in the NFL. Lindenwood defensive coordinator Eric Inama, in a Glazier clinic, lists being balanced against run and pass and allowing an 8 man box among its positives.

It also protects the deep ball. With three deep defenders, the glossary calls Cover 3 stout against the deep pass, and because the outside corners effectively play man against vertical routes, it tends not to give up as many easy completions as most zone defenses.

The seams, the flats and the curl-flat squeeze

The soft spots are well known. Lindenwood's Inama lists the short passing game and the four vertical passing game among Cover 3's negatives. The glossary's seam entry says Cover 3 is often susceptible to seam routes because of the stress they put on the free safety, and one of the most popular answers is four verticals: four receivers go deep at once to stress the seams between the free safety and the corners. In the Play Designer's version of four verticals, both outside receivers run a go route and both slots run seams.

The flat defenders get stretched next. Bowen points out that the strong safety and Will cannot get beaten outside by a flat route, which is why quarterbacks hold the ball until the defender breaks to the flat, then throw the curl route behind them. NFL.com analyst Bucky Brooks adds wheel routes down the boundary as a way to put the curl-flat defender in a bind. Offenses also flood one side with three levels. Bowen's example is "Sail" (the Play Designer files it as Flood): a go, a corner route and a flat route to one side, hoping the strong safety shortens the drop or jumps the flat and leaves the corner route open.

The free safety gets tested too. Bowen describes a classic Cover 3 beater: a deep dig route to tempt the free safety, with a post route coming from the other side behind it.

Spotting it before the snap

Cover 3 is a single high safety coverage, like Cover 1, so the free safety alone will not tell you which one you are facing. The corners can help a little: the glossary says Cover 1 is typically paired with press man outside, while Bowen's Cover 3 install starts the corners around 7 yards off. Do not lean on it. From that depth, Bowen notes, the same corners can still jam in Cover 2, play Cover 4 or drop to the deep third, and Brooks notes Seattle's corners in their single high looks press on the single receiver side. The Play Designer draws them about 7 yards off with the free safety about 13 yards deep, but treat those as 440's drawn defaults, not a rule. The shell can lie too: Bowen's install starts in a two safety look and rolls to Cover 3 at the snap, and the glossary shows Baltimore showing Cover 4 before rolling to Cover 3.

What each spot has to master

Corners: get to the outside third with outside leverage and your back to the sideline. Bowen's warning is blunt: if you get beaten outside, you have no help. Keep outside leverage and use the free safety as your help inside. 440's zone drop drill reps exactly this as a deep third bail for defensive backs, and the backpedal drill builds the pedal you use when you play off.

Free safety: you are the top of the defense. Stay deep enough to get over the top of a vertical from the outside, and do not chase intermediate routes. Curl-flat players: against the run, contain and force the ball back inside to your help; against the pass, work through the curl without letting anyone outflank you to the flat. Hook players: Bowen has the Mike and Sam playing the inside seam-hook. Derrick Ansley, who coached defensive backs for Nick Saban, defines the hook zone as 10 yards from the line of scrimmage and 2 yards inside the hash marks; Inama's drop spots put the hook-curl and curl-flat at 8 to 12 yards. The linebacker plan covers those drops as hook/curl reads.

Draw it against Cover 3

Open a concept from this page already lined up against Cover 3, then move players and routes to test it yourself.

• Four Verticals vs Cover 3Four receivers stretch the deep zones.Open
• Curl-Flat vs Cover 3Curl over a flat: simple high-low on the flat defender.Open
• Flood (Sail) vs Cover 3Three levels to one side: go, corner, flat.Open

Cover 3 FAQ