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Football 101: How a quarterback ‘reads’ a defense (aka Defensive coverage schemes)

Football 101 returns with a look at how a quarterback reads a defense pre-snap.

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Our Football 101 series continues today, attempting to better help all of us as fans of the game better understand what we are seeing on Sundays (or Saturdays, Mondays, Thursdays, etc), as well as what analysts are talking about throughout the week. Today’s Football 101 topic looks at the defenses that are being used, how a quarterback "reads" them, and what "Cover __" means.

Essentially, we are going to build this based on how a quarterback would read the defense. Before the offense snaps the ball, a quarterback has a lot of things to worry about and decisions to make. The offensive play caller may have made a decision on what play will work in the down-and-distance facing the offense, as well as what tendencies the defense plays based uon formation and that same down-and-distance. The quarterback, as the huddle breaks, now takes over (and assuming he has the ability to audible, he could change the play).

You will often hear the quarterback and/or center yelling out a number and pointing at a linebacker. This can included "is the mike" in the call as well. Basically, they are establishing who is the middle of the defense (typically the middle linebacker, thus the "mike" call), which aligns the blocking scheme for the offensive line, tight ends, and running backs.

The quarterback is also looking to figure out what kind of coverage a defense is running for that play. To do this, a quarterback will start at the deepest part of the field and move toward the line of scrimmage. Reading the locations of the safeties, cornerbacks, and the outside linebackers will help a quarterback determine if the coverage is man-to-man or zone, and where the holes in the defense should be.

Again, this is all before the snap. After reading the defense, a quarterback could already begin eliminating routes being run by receivers, or know of an option to a route being run that he expects to see from a receiver. You will also start to see hand signals or the quarterback making calls out to the receivers to let them know what he is seeing and what he wants them to do.

We have covered a large part of this topic before, in this coverage shells Football 101 post, but we will have to re-visit the coverage shells in order to understand what a quarterback is looking for to diagnose the defense.

So, how does the quarterback make a decision based on the positions of the safeties and cornerbacks? It is all about how many defensive backs are deep versus how many are close to the line of scrimmage - and then what some of the other players are doing.

Cover 0

Cover 0 is a pretty easy coverage to define. It means there are no safeties deep. This typically means a man-to-man scheme for the defense, with all the defensive backs up close to the line of scrimmage with a specific player responsibility. This alignment also can signal a blitz coming from the defense, as there are extra defenders compared to the number of receivers available for the offense (an offense has a maximum of five receivers available after five offensive linemen and one quarterback is taken out of the 11 total players an offense can have).

Cover 0 is a strong run defense, since all 11 defenders are near the line of scrimmage. It can be attacked through the air, however, as there is no "over the top" help for a cornerback from a safety deeper down the field. Because of the "island" effect of one player defending one receiver, look for the defensive backs to use an inside leverage (aligned slightly inside the receiver they are covering) to try to push the receiver’s route toward the sidelines, congesting the field, using the sideline as an additional defender, and keeping the receiver from the open deep-middle of the field.

Reading the indicators

To read this coverage, a quarterback should recognize the free safety moving toward the line of scrimmage. A defense will try to hide this for as long as possible, not wanting to tip off the open deep-middle or where the blitz could be coming from.

Cover 1

You can probably already figure out what the difference between a Cover 0 and a Cover 1 is. The one indicates one safety (the free safety) deep, typically between 12 and 15 yards beyond the line of scrimmage. The strong safety will move to about five yards off the line of scrimmage, aligned over the tight end. The cornerbacks will be in man coverage on their respective receivers, and typically will be playing press.

This coverage can also be called "man-free," indicating the defense is playing primarily man-to-man, but rather than the free safety being close to the line of scrimmage to allow for an extra blitzing player, he is back deep to provide for coverage help. There are still plenty of ways to get after the quarterback, with one player available to blitz (five receivers covered, plus the free safety, allows for the four defensive lineman plus one to rush the quarterback). The other option - and this is the one that makes Reshad Jones money - is to allow the strong safety to remain unassigned and not tagged as a blitzing option, but instead allowing him to freelance toward wherever he feels he can best impact the play; this type of role is typically called a "robber" which could make an analyst describe the defense as "Cover 1 robber."

Reading the indicators

To read this coverage, a quarterback will identify the free safety deep, as well as at least one linebacker in man coverage and the strong safety up toward the line of scrimmage. Those inside defenders will likely play with an outside alignment in an effort to force their responsibilities toward the middle of the field, where the free safety can assist. The cornerbacks on the outside will still be on islands, and will look to use inside leverage to add the sideline as a defender. Changing to a running play could be the right move here, with the receivers immediately tying up their respective defenders, the offensive linemen each picking up one defender (the four linemen plus a linebacker) and the running back being asked to make one player miss (or running the play away from that defender) while the free safety is deep. This could also be where sending a man in motion from one side of the field to the other, or half way and back, could help the quarterback diagnose what the strong safety is doing on the play.

Cover 2 (Man)

Again, the number gives away the basic read in this defensive scheme: two safeties, both deep. The safeties are probably about equal in depth, about 12 to 15 yards beyond the line of scrimmage. The cornerbacks are probably still pressing their receivers, and are in man-assignments. (Cover 2 is like the transition zone between basically man coverage versus basically zone coverage, so we will talk Cover 2 (Zone) momentarily.)

Basically, this is the same as a Cover 1 scheme, except now the two safeties split the field in half deep, giving support to both sides of the field. Cornerbacks are able to be more aggressive on their receivers, both in jamming them at the line of scrimmage and on trying to jump a route, because they know they have safety help over the top.

Cover 2 (Man) can be attacked on the ground - especially if you have a running quarterback. The receivers and tight end will take their defenders (cornerbacks and linebackers) away from the line of scrimmage. The two safeties are deep, and the four defensive linemen are matched up against the five offensive linemen. That leaves one linebacker to account for the running back and quarterback. If the running back goes out on a receiving route, the quarterback can read opening in the middle of the field, and determine he wants to run the ball and pick up yards that way.

The deep-middle of the field is vulnerable in a Cover 2, where the two safeties are helping the cornerbacks on the sides. This is where a seam-threat tight end becomes a huge offensive weapon. As tight ends have turned into the Rob Gronkowski mold, they have been able to take advantage of the middle of the field against Cover 2.

Reading the indicators

The two safeties are both deep. The cornerbacks and linebackers in man coverage will typically align themselves with outside leverage, looking to force the receivers into the zones being patrolled by the safeties (of course, if a receiver goes too far inside, he now can find that hole in the zone in the middle of the field, so there is a risk for the defense - and an opportunity for the offense if they have read the indicators correctly).

Cover 2 (Zone)

Like the Cover 2 (Man), the Cover 2 (Zone) puts two safeties deep in zone coverage. Now, however, the rest of the defense is also switching to a zone scheme. The cornerbacks could be playing off the receivers, or they could press the receiver, jamming him at the line of scrimmage, then transitioning into a zone coverage in the flat. The linebackers each have a zone of coverage as well, with the outside linebackers covering behind the cornerbacks’ flat zones, and toward the middle of the field, while the middle linebacker has the middle of the field.

The run can again be exploited here, as the linebackers move away from the line of scrimmage to make sure they are covering their zones. Short passes are harder to do against the zones, because there are defenders moving into the flat and the slant areas on the field. Getting a receiver past the cornerbacks before the linebackers are set, or into the holes in the zone between the cornerback and the safety is key. If a team has multiple deep-threat options, this defense will have problems if they break through to overwhelm the zones of the safeties.

Reading the indicators

Initially, this is going to look like Cover 2 (Man), but there are small differences that can be picked up. The cornerbacks may not be pressing. The linebackers may not have the same outside leverage they had in man, instead being closer to the middle of the field before breaking into their zones. Again, motion can help determine if the coverage is man-to-man or sonce.

Tampa 2

We are not going to spend much time on the Tampa 2, but it does deserve a mention here, because it gets so much discussion by analysts. Essentially, a Tampa 2 is a Cover 2 coverage, but takes the middle linebacker and adds a zone in between the safeties (probably not as deep, but deeper than the linebackers normally would play a zone) to try to defend the hole in the middle of the field.

Cover 3

We are purely zone now, but we are also in a defense that is designed to stop the deep passing game as well as prevent runs up the middle. Here, you are going to have the free safety deep, again about 12-15 yards, with the strong safety moving up toward the line of scrimmage, probably about 5 yards back with the linebackers. The cornerbacks are going to play off their receivers (for the most part).

The free safety and cornerbacks then split the deep portion of the field into thirds, with each one of them responsible for their zone. The linebackers then take the underneath zones, along with the strong safety, essentially breaking the field into quarters here, with each responsible for a section. The strong safety is also up closer to the line of scrimmage to help against the run - again, a Reshad Jones specialty - and the linebackers will all start the play near the middle of the field, again as a run stopping measure.

Short, quick throws from the offense are going to make money here. The linebackers or strong safety responsible for the outside short zones will likely be moving toward the zone from the middle of the field at the snap, while the cornerback will be trying to break back into his deep zone. This might be the dreaded "nickel-and-dime" passing game that everyone loves to hate, but it is going to be effective against Cover 3 (most of the time).

Defenses can adjust the Cover 3 to keep the cornerback in press coverage, allowing him to jam the receiver before breaking back into his deep zone coverage. This will keep the quarterback from being able to complete the quick pass and it will give the linebackers and strong safety a chance to get into their zones, but it also risks the cornerback being beaten into his zone by a fast receiver, or someone who plays through the jam. Defenses need strong, quick cornerbacks to be able to run a "press-Cover 3," and they have to have a free safety who can react quickly and instinctively to pick up any slack left by the cornerback (think Seattle Seahawks here).

Reading the indicators

The safeties are aligned like they are in a Cover 1 formation, but the linebackers are inside the box, rather than aligned against a specific receiver. The cornerbacks are likely playing off their receivers, preparing to run back into their zones. Quick flat routes where the receiver can get the ball without much coverage in front of him and then transition into running after the catch is the best play design here.

Cover 4

Cover 4, or "quarters" defense, is designed to stop (or prevent - see what I did there?) deep passes. The two safeties and two cornerbacks split the deep portion of the field into quarters, with each responsible for one area.

The linebackers underneath then split the field into thirds, each taking an area across the intermediate depth of the field. The flats will be basically abandoned by the defense, allowing for short passes, and the possibility of a running attack, but the deep defenders are expected to be able to cover ground quickly to move back up toward the line of scrimmage.

The linebackers could be asked to blitz in a Cover 4 as well, though it does become risky for the defense. Typically, if the linebacker rushes, a defensive end could drop into zone coverage.

Reading the indicators

The defense is going to initially look like a Cover 2 - unless they are truly going to a prevent defense, in which they will likely just start with the four defensive backs deep. In a conventional Cover 2, the two safeties will be deep, and the cornerbacks will likely also play off their receivers, ready to move back into their respective zones. The linebackers may start to spread out to better cover their zones prior to the snap.

Cover 6

If you have been following our scheme builds, you will be ahead of us at this point. Cover 6 is six zones deep - no, it’s not. Cover 6 is actually a combination of Cover 2 and Cover 4 (the six coming from two plus four). Half the field is in Cover 2 - typically the side of the field closest to the sideline (the "boundary" side of the field). The other half is in a Cover 4 scheme. The free safety covers the boundary side of the field in a Cover 2 system, while the strong safety and a cornerback split the other side of the field (the "field" side) in the Cover 4 style. (Of course, the safeties could have opposite responsibilities, but the free safety is typically the better coverage option, so he gets the Cover 2 side.)

The strengths and weaknesses of the Cover 6 are the same strengths and weaknesses of the Cover 4 and Cover 2 systems, depending on where you are looking on the field.

Reading the indicators

The two sides of the defenses will look different. The safety and cornerback on the Cover 4 side will both be deep, while the Cover 2 side will have the safety deep while the cornerback is closer to the line of scrimmage.


Obviously, there is a lot more to the defense than just this, but it is at least a start to what a quarterback is trying to see pre-snap. Defenses will also disguise their look, giving one initial impression before they switch to something else. Defenses can "roll" from one initial look (like a Cover 2) into the actual scheme (like Cover 1) by aligning the safety in one place, then moving him just before the snap or as soon as the ball is snapped. There are also hybrids of the schemes, plus the nickel and dime packages that can change things. There is a lot of complexities to the defenses, and this is just one small part of a quarterback reading what he is seeing pre-snap, but it is a starting point.