Xs and Os: The Three-Deep Zone Defense (Cover 3)

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The cover 3 pass defense has the cornerbacks and free safety splitting the deep half into thirds.
The cover 3 pass defense has the cornerbacks and free safety splitting the deep half into thirds.

Continuing with our series of defensive coverage shells, this week we’ll take a closer look at the three-deep zone defense, which is more commonly known as the cover 3.

Previously, we looked at the cover 1 and cover 2 defenses.

Green Bay Packers defensive coordinator Dom Capers predominantly prefers the single-high safety look, but he has deployed the cover 2 shell frequently over the years.

However, the Packers don’t use the cover 3 all that often, but it’s a defense that every NFL team must have in their arsenal because what it brings to the table.

Of course, this article comes with my standard disclaimer that this is an oversimplification for illustrative purposes only.

Cover 3 Defense Defined

When defending the field, the defense usually divides the area vertically into “halves.” The underneath half typically extends 7 yards from the line of scrimmage and the deep half usually extends 15-20 from the line of scrimmage.

In the three-deep zone defense (cover 3), the free safety and both cornerbacks play zone defense and each guard a third of the deep half. They must cover any receiver entering their respective third of the field and drive towards to the ball once it is in the air. Additionally, they must carry the receivers vertically all the way to the goal line.

The GIF below highlights the assignments.


Strengths of Cover 3

There is no perfect defense in football. If the defense sells out to stop the run, they are extremely vulnerable to the pass. Likewise, setting up a strong back end to guard the pass makes them susceptible to the pass.

The cover 3 is a compromise defense of sorts. Because the deep third is covered by the free safety and both cornerbacks, the strong safety is free to align in the box.

This means the defense can play eight in the box to stop the run. The front seven (defensive line and linebackers) are in the box in addition to the strong safety.

In a nutshell, the cover 3 allows the defense the flexibility. It can be considered a “jack of all trades” defense. It is a very popular run defense, with pass flex, in the NFL because it allows the defense to pack eight in the box and still drop seven into zone pass coverage.

Weaknesses of Cover 3

The cover 3 is a full zone defense. In contrast, the cover 1 and cover 2 allows the defense flexibility to play man-to-man or zone in the underneath half, including various blitz packages. Also, the cover 1 and cover 2 allow the safeties to provide double coverage over the top.

Since the cover 3 is usually full zone, there is no real opportunity to blitz. Also, since the underneath half is playing zone as well, the deep thirds cannot usually provide double coverage over the top. The underneath defenders must release their receivers once they clear their zone.

Additionally, the cover 3 relies on linebackers to cover any receiver in their zones, who may be quicker and more athletic than they are. As such, the cover 3 is vulnerable to quick and short passes underneath.

Aligning and Playing the Cover 3

When we previously covered the cover 1 and cover 2, we didn’t consider the underneath zones all that much because the cover 1 and cover 2 are basically protective shells over the top of flexible underneath coverages.

However, the cover 3 is typically a full zone, so the deep zones work in tandem with the underneath zones. Each of the zones is assigned to guard specific pass routes, so we must review the route tree below.


In the route tree above, the receiver breaks his routes at different depths. Routes 1 and 2 are part of the three-step game. That means the quarterback take a three-step drops and immediately fires the ball to those routes.

The underneath half is responsible for the three-step game of wide receiver routes, as well as any routes being run from backs from backfield.

Additionally, the underneath zone must be on alert for the 5 and 6 routes (part of the 5 and 7 step game, explained below) because these are defined as comeback routes, where the receiver previously cleared the underneath zone but returns to it while the ball is in the air.

The deep zone is responsible for the 7-9 routes. These are part of the 5 and 7 step game, meaning the quarterback backpedals 5 or 7 steps before throwing the ball.

What defines the 7-9 routes, and the deep zone responsibility, is what is called the “move area.” The move area is the point at which a vertical receiver will break his route in the 5 and 7 step game. The break point varies by offense and play situation, but it generally happens between 10 and 18 yards from the line of scrimmage, making the deep zone responsible for defending the move area.

Now that we understand the basic route assignments, we can look at how the defense aligns before the snap of the ball.

Typically, the free safety shows a singe-high look and the strong safety aligns in the box on run alert. Both cornerbacks play in the box, but may give the wide receivers a generous cushion. They have the difficult assignment of providing run support, but quickly bailing deep into zone coverage on a pass play.

At the snap of the ball, the defense must recognize run or pass. Assuming it’s pass, the defense must rotate into the full zone. Because the linebackers must recognize pass and drop into their zones, they are a weak link in the quick passing game.

The free safety and both cornerbacks must quickly backpedal to achieve depth. The free safety plays between the hashmarks and the cornerbacks play atop the numbers.

The will linebacker is responsible for the weak side flat and the the strong safety is responsible for the strong side flat.

The mike and sam linebackers are responsible for the middle zones.

The GIF below highlights the zone assignments.


For simplicity, we are neglecting the back and tight end routes. However, you can see the major zone assignments.

The will linebacker and strong safety cover the flats and are responsible for the 1-6 routes. The cornerbacks and free safety are responsible for the 7-9 routes.

The cornerbacks and free safety must be conscious of the move area and anticipate the receivers’ breaks and drive to the ball in flight. Since they have no help over the top, the will often play out of phase to apply leverage and have position to drive back to the ball.

The will linebacker and strong safety must carry the receivers through the zone, sometimes in a trail technique. By playing a trail technique, they force the quarterback to elevate the ball over them, which is a more difficult throw. It also allows the cornerbacks the ability to drive downhill towards the ball in the flight.

Also, by playing a trail technique, the will linebacker and strong safety are in position to cover the comeback 5 and 6 routes. They are in front of the receiver and the cornerbacks can drive downhill.

Other times, if the linebackers get enough depth quickly, they can play behind the receivers and carry them through the zone while the play unfolds in front of them. This is desirable for the screen and draw game, as well as short squat routes.


The cover 3 is a good all-around defense because it gives them flexibility in defending the run and pass. It allows them to have eight in the box while providing full zone pass security. It allows the defense to always be facing the ball and having the play unfold in front of them. It doesn’t allow for blitzing or double coverage, so everyone must execute their assignment to avoid getting beat.


Jay Hodgson is an independent sports blogger writing for AllGreenBayPackers.com and WISports.com.

Follow Jay on twitter at @jys_h.


28 thoughts on “Xs and Os: The Three-Deep Zone Defense (Cover 3)

  1. Sorry but that play you referenced is not cover 3. Its actually single high Safety.

    It starts w/ cover 2 look at the snap. If you look closely Shields is in press man formation doesn’t press but falls off to protect against the deep ball since he isn’t expecting help over the top knowing Burnett (the Safety on is side) is moving forward to play the TE. On the other side Tramon and Hyde are playing off man (you can tell since Hyde reacts to the WR’s inside breaking route) instead of Hyde passing his WR off to an inside Safety and Tramon staying w/ the WR at the top of the screen not even watching the QB. As the play continues, Burnett moves up to play the TE in man, leaving Richardson as the single high Safety (shaded to the top of the screen since 2 WR and the TE are lined up there). Shields runs w/ Jeffrey throughout the play. Tramon turns his back to the QB to run w/ his WR (presumably Marshall) down the sideline and Hyde reacts to his WR inside break. In zone Hyde wouldn’t respond to the WR breaking inside and Tramon would stay deeper than the WR instead of turning to run w/ him.

    If it was 3 deep safeties, Shields would not have been in press formation at the LOS and run w/ the WR, he would have started deeper and kept his eyes on the QB. Instead he is playing the WR, shadowing his route. He wasn’t even expecting deep help since he was running even w/ Jeffrey the entire way instead of playing on his hip. Tramon (after the play starts) never even looks at the QB, once he engages the WR he actually turns his back to the QB to run deep and disregards the QB and Hyde only reacts deep once the ball is thrown, otherwise he was sticking w/ the slot receiver.

    Its starts as cover 2 at the snap, but Burnett clearly has man coverage on the TE since he steps up from the beginning/pre-snap. If it was 3 deep the CB wouldn’t be running w/ the WR they would be keeping their eyes on the QB and backpedaling, staying deeper and responding to WR entering their zone.

    Last year the Packers started giving the CB’s the option of playing press or off man based on the playcall or matchup they had in man coverage. That explains why Hyde and Tramon are in off coverage playing off man while Shields is in press formation.

    I doubt that the CB’s would be used as 2 of the 3 deep. It would be both Safeties and either a CB or more likely another Safety brought in.

    The Packers only use cover 3 when its going to be a longer passing play and everyone is playing zone. Shields, Hyde, Tramon and Burnett are all playing man coverage.

    This play is 3rd and 17 so it fits as a play the Packers might play 3 deep, but the CB’s don’t respond as if they are in zone. Shields wouldn’t be in press at the LOS and run w/ the WR he would be backpedaling, Hyde wouldn’t react to the WR inside break, Tramon wouldn’t turn his back to the QB to run w/ the WR and Burnett would stay deep and a LB would play w/ the TE off the LOS.

    Shields, Burnett, Hyde and Tramon all react as if in man coverage, not zone.

    1. Like I originally said, I couldn’t find a clip of straight cover 3, so I tried forcing a round peg through a square hole. The reality is they didn’t align in cover 3, but the defense played pattern matching flex zone. The routes didn’t allow them to play cover 2 or 2 man, so they shifted on the fly. After they shifted, the look was the equivalent of a cover 3. Yes, the corners bailed in man, carrying the receivers vertically. But, they did so without safety help. If if was cover 2 or 2 man, both safeties would have bracketed the verticals. Since Richardson is in the deep third all by himself, he has to be in cover 1 or cover 3. If cover 1, he would have rotated over earlier to the verticals. But, he didn’t, so that means he is responsible for the middle third himself.

      Granted, it wasn’t the best video, but it shows the thirds assignment more or less. The pattern matching was the difficult tell. I don’t think it was man because Richardson wasn’t helping anyone.

      Perhaps sometime down the road I’ll write a post about sight adjustment pattern matching.

      1. Cardinal sins were made all over the place for it to be any kind of zone. Shields would not have lined up in press. Hyde sat on the inside break by the slot WR. Tramon after the play started had his eyes strictly on his WR and actually turned his back to the QB (dead giveaway of man coverage). Richardson was the single high safety shaded to the top of the screen since the 2 WR and TE lined up there. Burnett would have been a Deep Safety in 3 deep coverage.

        Nothing about what Shields, Burnett, Hyde or Tramon did was indicative of any kind of zone. Richardson didn’t have a man since he was the single high safety and shaded to the top due to the overload, basically leaving Shields on an island. Burnett, Hyde and Tramon all play man techniques.

        There were 3 vertical routes by Jeffrey, the TE and Marshall. Only the slot receiver broke off and Hyde stopped in his coverage and started to break on it before seeing the ball thrown deep. Richardson couldn’t cover anyone since there were 3 verticals 2 down the sideline and the TE up the seam.

        If it were a zone coverage w/ Shields, Richardson and Tramon as the 3 deep they would have all been backpedaling facing the QB the entire time. Shields runs w/ Jeffrey even tho keeping inside technique and uses the sideline as a defender while he ran w/ Jeffrey since he had no help at all w/ Burnett moving up and Richardson shade top . Tramon actually turns his back to the QB which is a dead giveaway of man.

        The routes of the WR didn’t dictate the coverage, the CB’s including Hyde and Burnett all played man techniques. Even if it were what you call pattern matching the techniques by Burnett, Hyde and Shields and Williams outside are pure man.

        Only Richardson was in deep zone (single high) and he was moving to the deep middle since Cutler was looking to Jeffrey nearly the entire play except for a brief glance to Marshall early.

        1. We’re just going in circles, so I took the dang video down. I’d rather not dominate the discussion by arguing over semantics. That’s not productive.

          But, I’ll conclude with a few points.

          1) Plays are only “pure” in the playbook. As they develop, they are dynamic and have different end results.

          2) Zone coverage is man-to-man coverage, but only over a specific area. They play the man with the zone.

          3) The play I posted concluded as a cover 3 because at the end of the play, deep half was covered in thirds. The corners carried the outside verticals deep and Richardson was covering air in the deep middle. If it was cover 1, he would have helped at least one of the verticals, even if he had blown his assignment–he would have covered more than air. But, he was assigned to cover the center vertical, even if that meant it was air at the moment. He only rotated over once the ball was in the air. Cover 1 would have him rotating long before the ball was in the air.

          4) Because plays are only pure in the playbook, it’s dang near impossible to find videos of pure plays as they unfold. Defense reacts to offense, who then reacts to defense, who then reacts to offense.

          I’ll do my best to find better videos in the future.

          1. 1. Of course they develop as the play continues. But the video clearly showed man coverage techniques by Shields, Tramon, Hyde and Burnett to a slightly lesser degree the TE never was a credible threat.

            2. Zone is playing your area first not man first in your zone. Zone is being worried first for your zone and spacing, then reacting to a potential receiver.

            3. Saying its cover 3 at the end doesn’t make sense since the defenders all stayed w/ receivers during the play. Richardson responsibility isn’t to any vertical, not w/ Burnett on the TE and the outside CB’s playing the vertical sideline routes. His responsibility is to stay deeper than any receiver to prevent anything over him.

            5. The defense didn’t adapt their technique to the offense, they played man techniques throughout.

            Sorry, but that play showed nothing of zone coverage. It was strictly man coverage w/ single high safety playing deep enough to prevent a long gain and Richardson had to honor the fact that the top side of the field was overloaded.

            1. 2. Zone is playing your area first, not man coverage in your zone. Zone is being worried first for your zone and spacing, PLAYING THE QB second, then reacting to a potential receiver.

              1. While it’s not a pure cover 3, it’s not pure man like you say based on the following:

                1) Richardson is covering air in the deep third.

                2) Bush drops to the flat first without covering a man. At the snap, he automatically dropped to the flat without ever reading a route.

                3) 3rd and 17 is not a man tendency. The d and d says play zone and keep the play in front of you, especially since the d and d screams draw/screen.

                4) The zone defender does cover the man in the zone as man-to-man. You need proper spacing, must play the QB as you say, but they still must guard the person in the zone, otherwise, what’s the point?

                5) My choice of video doesn’t diminish the the overall article. I was very clear in my disclaimer that it wasn’t the most ideal video, but it did show the field getting defended into thirds, which is the whole spirit of the cover 3.

              2. 1. Richardson covering air? What are you talking about… As the single high safety he is playing a zone basically. That zone consists of everything deep. He isn’t supposed to be covering a specific person.

                2. Bush drops into the box and then takes Forte in man coverage, he isn’t playing a zone. He’s just another example that its man coverage.

                3. Maybe the tendency isn’t man w/ single high on 3rd and 17 but sometimes you break tendency, and clearly this was man coverage w/ single high safety. Even the ILB who were blitzing means it had to be man coverage.

                4. In zone defense the defender doesn’t follow the man in his zone, he has to maintain the integrity of the zone, watch the QB and be aware of players in his zone, not cover man for man in his zone. WHat if 2 players are in his zone? The offense could also then run 2 adjacent zone defenders in opposite directions to open a gaping hole, compromising the integrity of the coverage in particular and the defense as a unit. In zone the whole Defensive coverage has to move as a unit, not individuals each in man in his zone.

                Your choice of video was terrible since it was man coverage w/ single high safety. Which was what I responded to. Its nothing more than coincidence that is looks like the field is divided into 3rds, since the CB’s both had to defend vertical sideline routes.

                Your continuing to try to make your case especially using Bush as an example isn’t helping you. Bush steps forward into the box, not into the flat and when Forte releases between the LT and LG Bush picks him up in more man coverage. Clearly Bush’s responsibility was man coverage on Forte!

                I didn’t even say anything about the rest of the article. Hell I barely read it, just looked over some parts of it. My whole point was the video from the beginning, since its MAN coverage all the way.

  2. Hey, just ignore him and he’ll go back in the bathroom with his mom’s aloe lotion

    1. It’s not trolling. It’s just a disagreement over what we see on the film, which is actually a common thing, even in NFL coaching rooms. The reality of it is unless we know the actual play call and the playbook diagram, no one knows the actual play when breaking down film.

      1. Well, that’s assuming it’s a dynamic play. If it doesn’t involve sight adjustments, a straight forward play is easy to diagnose. The problem is almost every NFL play is dependent upon sight adjustments and audibles, bot on offense and defense.

  3. By the way, Pro Football Focus, which is a very reputable organization, says this defensive alignment is cover 3. It’s similar to what the Packers showed against the Bears in the play in the video. The routes were different, but the defensive alignment is very similar. Look at the CBs, SS, and FS.


    According to your thoughts, this play would be man free. But, PFF has it broken down as cover 3.

    I rest my case.

    1. And Matt Bowen, who actually played Safety in the NFL would conclude its single high w/ man coverage. He calls the off man alignment of the 2 CB’s, and shows the diagram right down to Shields being in press and playing what he calls inside slat technique to try to pin the WR to the boundary and limit the route options of the WR, in this case Jeffrey.

      Only difference between the alignment he shows on his diagram for is that there is only one RB and a TE next to RT. Burnett as I noted comes forward to play man vs the TE.

      If both ILB blitz there is no way you can play zone behind it.


      Don’t know about anyone else, but I’ll take Bowens info over the talking heads at PFF every day of the week.

      Simply have to watch all the CB’s. Hyde plays exactly what Bowen calls a “flat footed” coverage vs the slot WR. Shields plays exactly what Bowen calls inside slant technique vs Jeffrey. Burnett come up to play the TE who otherwise had a free release. Tramon turns his back to the QB and runs w/ the WR after Marshall eats the cushion. Bush steps into the box and picks up Forte on his inside release. Those are all man asignments.

      Richardson steps into the deep single high to keep things in front and he has the ability to come forward in an instant if a short pass is completed to help make the tackle short of a 1st down.

      Its text book from his illustration of Off Man Alignment for cover 1.

        1. Man…. smh… just…. smh..

          Stroh. You have just earned yourself the right to be completely ignored by yours truly. (not that I’m sure you care) For the next month.

          1. Ignore if you want, there isn’t a person hear that knows anything close to Matt Bowen and he showed a perfect diagram of the coverage right down to the techniques.

            I tried to be courteous, but he can’t be told that he is wrong. The coverage was Cover 1 Man. Period! End of Story!

          2. I dare anyone to get that play Bowen or someone of similar knowledge and I’ll guarantee they call it cover 1 Man.

  4. Looks like Cover 3.1415927… to me, i.e. “cover pi” That’s why Capers defense is “as easy as pie”.

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