I put up an overview of attacking Cover 2 defense some time ago based upon a book and some coaching videos I had watched. In hindsight I probably should have painted the overall picture before discussing just one type of zone coverage. Here are some very, very general comments and graphics that related to the basic nature of zone coverage schemes in football. In addition I'll put up a another post on basic concepts for attacking zone coverages as well. The details of secondary coverage are far more varied and confusing than I will present here but we have to start somewhere and the basics are usually a good first step. Most of the basics of what I'll describe are outlined in Steve Axman's book Attacking Coverages with the Passing Game. Coach Axman some of you might remember from the four years he spent as QB coach at Washington or the less successful one season he spent at UCLA as offensive coordinator. The book does a nice job of explaining the basics so if anyone is interested in learning more I would suggest purchasing it from either Amazon.com or CoachesChoice.com.
The initial thing that coaches teach about recognizing zone coverage schemes is the notion of "0", "1" or "2" safeties deep. This is a quick way to start categorizing the secondary and the way they are lined up. "0" safeties deep is simply the case when the QB looks at the center of the field and finds that everyone is up on the line of scrimmage and no one is back deep for support. This is a pretty rare case and normally indicates that the defense is going to blitz the quarterback by bringing more defenders than the offense can block. Of course it could be a fake but we'll stick to the simple case first. There are two slightly different definitions of blitzing to keep in mind. One is the stricter definition where the defense brings one more person than can be blocked by the offense. For example if the offense has six men kept in for protection the defense must send seven people in order to make it a true blitz. The other looser definition is when the defense simply sends one or two people other than the normal four down lineman (assuming they are a 4-3 base defense team). "0" safeties deep is normally the extreme case where everyone is on the line and threatening to blitz. The Philadelphia Eagles of the NFL probably due this under their defensive coordinator Jim Johnson more than anyone in the game today. It is a high risk and high reward strategy only used a few times a game and is predicated upon creating pressure quickly. The WR's will have man coverage and the QB will be looking to get rid of the ball in a hurry to a back or outlet receiver. Here is a sample picture of what I mean by a no safeties deep look and Cover 0. The corners are playing slightly off here by necessity since getting beat deep by even one step would result in an almost sure touchdown.
"1" safety deep means there will be a single safety in the middle of the field when the QB is under center and scanning the defense. With respect to basic zone coverage there are two basic cases for this instance and a couple of derivatives. Let's start with the concept of Cover 1 zone defense. Cover 1 is like the picture below where only one safety is deep and the rest of the defenders are closer to the line of scrimmage. In this zone defense the people underneath will play man defense and the single safety deep will have certain responsibilities depending upon the action after the snap of the ball. Generally he will guard the deep middle of the field on pass plays and in some cases he may to asked to provide some double team support if there is a dominant WR in the game that needs to be defended closely.
The defense would look about like this to the quarterback although of course the minor details would all depend based upon the exact formation and alignment of the offense and defense. Normally the CB's in Cover 1 play an aggressive press defense at the line of scrimmage and try to bump the WR during his first few strides. The idea is to disrupt the pass pattern and hinder the timing of the play. The danger of Cover 1 of course is that any small mistake and the defense could surrender a big play. Against run dominant teams that have a weaker passing QB however this can be an excellent way of putting eight men in the box on different plays. I have seen USC do this quite a number of times over the years when they feel this provides the best defensive match up and way to attack. The following picture is an example of Notre Dame using a Cover 1 defensive shell look before the snap of the ball. The Corner back in the lower part of the screen plays tighter on the WR since there is no danger of being picked by other receivers on the play. At the top of the screen they have to give more ground accordingly.
Cover 1 Shell Look
The other main form of "1" safety deep is Cover 3. Cover 3 is similar to Cover 1 in that the QB will only see one safety deep in the middle of the field. However it differs from Cover 1 in that it is a three deep zone and not merely a single safety deep zone. On TV this can be very difficult to distinguish due to the way it is played and the narrow viewing angle. In extreme theory a Cover 3 alignment shell with will look something like this next picture.
In reality it can often look slightly different. Regardless the main difference between Cover 3 and Cover 1 is that after the snap the CB's will back off and not press the WR's at the line of scrimmage. In some cases they even start aligned seven or eight yards off the WR even before the ball is snapped giving the receiver a cushion. Why do teams do this? It makes sense on certain down and distance situations. Coaches will tell the two CB's and the FS for example to drop to a distance of say 10 yards and then keep everything in front of them. For example this strategy makes sense in cases like 3rd and 10 for example where the defense is willing to concede the short 5-7 yard underneath routes in front of the defenders. If the WR runs a deeper route the DB's of course have to go with him and not get beat deep. In concept however the secondary is just dividing the deep part of the field into thirds and playing a zone defense. Here is a look at a play that wound up being a Cover 3 defensive scheme. It looks similar to Cover 1 but after the snap the retreating movement by the CB's identifies the nature of the scheme. Since there is no wide receiver to the right of the formation the DB to that side aligns outside of the tight end as an adjustment.
In reality there are of course derivatives of these defenses that I can not adequately show. Let's just consider Cover 3 for a moment. In pure zone based Cover 3 scheme the three DB's play a deep zone and the four underneath players normally play a four wide zone underneath. There are cases however when the defense plays the three deep zone in the secondary and plays man to man coverage underneath with the linebackers and strong safety for example. There is also the non-trivial decision of who plays deep in Cover 3 and how do they get there? By this I mean that the defensive coordinators love nothing better than to confuse the heck out of the opposing QB and offensive coordinator. They will do tricky things like line up in something other than an obvious form of Cover 3 and roll into this alignment with differing responsibilities. This has mysterious sounding names like "Cloud", "Sky", and "Rolling Thunder" in football circles (or serious football video game players). When the a cornerback rotates down and is in charge of defending the flats area it is called "Cloud" coverage. When a Safety has responsibility for the flats area it is called "Sky" coverage. Rolling coverages is the complex game of moving the defender to different locations after the snap of the ball to create confusion in the mind of the QB and the WR. For example the 1/3, 1/3, 1/3 secondary split about might shift to a 1/4, 1/4, & 1/2 split of the deep territory. Or a corner back might come crashing down after the snap while the free safety or the WLB goes flying back to occupy that space. Defensive coordinators and secondary coaches are all full of deceptive tricks they like to pull on the opposition all with the intent of creating confusion, delayed recognition, and hopefully an interception. Unfortunately the fans are denied this viewing angle on TV and the commentators usually don't mention it at all except in obvious cases where there was a big play one way or the other. (Note: For more information on this topic of Cover 3 and different variations Bill Arnsparger goes into excellent detail and provides graphics on pages 128-135 of Coaching Defensive Football.)
The other main category mentioned at the top of this post was the "2" deep family of zone coverage. This is more familiar with most fans since the press has figured out what it means and likes the sound of the scheme I suppose. Rarely does any team like USC or at the pro level spend any more than one third of the game in any specific secondary look. It is just too easy for the opposition to defeat if the defense is that consistent. A two deep family of zone coverages looks like the following.
In this case the QB will see two safeties deep in the middle of the secondary. They will divide the field between then into halves and provide deep support on any balls throw in the middle of the field or towards the outside. In pure Cover 2 zone the five defenders underneath also divide the field up into zones and each defend an area against a type of pass (e.g. hook, curl, flat routes, etc.). In some playbooks I have seen they have it worked down to exact yardage for example. The football field is 53 and 1/3 yards wide. If the ball is in the exact middle of the field that means the underneath defenders have 10 and 2/3rds of zone to cover. This means roughly 5 and 1/3 to their left and 5 and 1/3rd yard to their right if they position themselves correctly. They will cheat one way or other depending upon reads and offensive alignment. If the ball is on the hash mark to one side or the other it means they can cheat a little more sideways as well. This five under zone works well when defending against offenses that are predicated on the short underneath routes or with inaccurate QB's. A one yard mistake is the difference between completion and interception. Provide defensive pressure up front with only four down lineman and this seven person zone (2 deep 5 under) works wonderfully. With no front four pressure however it gives a good QB lots of time to find an open man. Here is a general example of a Cover 2 defensive shell. The exact alignments differ slightly due to the capability of the defenders and the nature of the formation.
| USC
Cover 2 Shell versus Oregon |
ND
Cover 2 Shell verus USC |
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A derivative of Cover 2 of course includes the 2 deep zone and 5 man under version of this defense. This will often be called Cover 2 Man Under for example. Different teams have different names. I have even heard it called Cover 7 by some coaches. To other programs Cover 7 means something entirely different. As deceptive tactic USC will often line up in Cover 2 and instead play Cover 1 for example as a change of pace to confuse the QB. Any time you see the strong safety (#4 Kevin Ellison in 2006) for example creeping forward around the snap it is a safe bet that USC is showing one look out of this shell and then really playing another...
Cover 4 defense is the other main type of zone defense in the "2" deep family of zones. Cover 4 is like Cover 2 in that two safeties are deep but normally the two corner backs are playing off the line of scrimmage as well. They can either line up tight and bail into this coverage or line up off the WR and play loose the whole time. The concept is simply to play a four deep zone across the back with the three LB's playing a zone underneath. This strategy is used when the defense is willing to concede the short throw and stop deeper passes on instances like 3rd and 12 for example. Or it might be used against teams that play a lot of multiple WR sets.
Often the depth and relative positioning of players makes it difficult to really tell which defense is being played - even for the QB. But that is part of the intent of all this to confuse the opposition into making a bad throw or mistake. In distinguishing the subtle differences between Cover 1 and Cover 3, or Cover 2 and Cover 4 for example the coaches often have the QB check the eyes and stance of the CB's. When teams play zone the corners for example are going to watch the QB more and pay less attention to the WR's before and right after the snap. When the defensive back is peering into the backfield it is a tip off they are playing zone. The positioning of their feet sometimes also gives away if the CB is going to quickly open their stance and hold ground in a soft zone or back pedal hard, turn, run and play deep. CB's that are 100% absorbed and locked onto the WR's are normally playing them in one on one coverage and studying the receiver to see which way he might lean or try to fake. Often subtle little things that the coaches and staff catch on film like this are big give aways regarding the actual defense on the field. This is the only good example of a Cover 4 defensive shell that I could locate. It is a picture from a Rams game from several years ago. On this snap the CB's dropped back at the snap to the depth of the safeties and created an evenly spaced 4 across zone. Often until the snap of the ball it is difficult to tell if the alignment is Cover 2 or Cover 4.
Here is one from the college level where Ohio State played the University of Washington.
The last major type of zone coverage I will outline is the infamous Tampa Two style of defense pioneered by Monte Kiffin. I don't see this defense played as much at the college level but it does exist and is used. Tampa Two is often and mistakenly used interchangeably by fans and the media with Cover 2. They are similar but they are different in the details. Tampa Two zone defense is really a sort of hybrid between Cover 2 and Cover 3 styles of defense. Here is a picture of what I mean.
Tampa Two starts out as a "2" deep zone but winds up as a semi-three deep zone scheme. This scheme is unique in that it asks the MLB and not a DB to retreat and play the middle deep part of the field as needed. Teams that opt to do this style of zone require a linebacker that can run as fast as any tight end or WR that might head up the middle part of the field. All zone defenses have "holes" in them somewhere that any good QB can exploit given time. Man coverage has different weak points entirely. One of the "holes" in Cover 2 is the deep middle of the field between the two safeties. To address this Monte Kiffin utilizes a linebacker like Derrick Brooks in Tampa and the Chicago Bears often use Brian Urlacher to protect the deep middle of the field on certain plays and situations. Both are rare LB's that can run with any tight end in the NFL for example and help cover the deep middle third of the field. This makes a QB think he is facing Cover 2 and in reality throwing into something else. This subtle difference is difficult pre-snap to read and might only be given away by either tendency analysis or in the detailed positioning of the MLB and his body posture or the width of the spacing between the two safeties. Even a yard in one direction or the other is all that it takes to tip off a play some times.
Rich Rodriguez the head coach of West Virginia made an insightful comment earlier this year in one of his speeches at a Nike Coaching Clinic. The days of playing any one primary defense in the secondary he noted are long gone. Play too much of any one thing in the secondary whether it be man or zone and you will eventually get burned as each one can all be dissected and beaten ten different ways. In the June 2007 edition of American Football Monthly Bud Foster defensive coordinator of Virgina Tech explains how the Hokies are having to shift more to "2" high safety looks as teams have figured out too many ways to beat their normal defense which was predominantly a "1" high safety scheme. Conversely I privately suspect USC has played relatively less Cover 2 defense than commonly assumed the past couple of years for the same reason. Only the coaching staff knows for sure and they are not going to comment on something of this nature. Today virtually every good high school QB coming into Division I football can now spot the differences between Cover 0, 1, 2, 3, 4 and the more common derivatives mentioned here. They also know many of the more exotic versions not mentioned as well. Credit good coaching at the high school level and an increasing wealth of instructional material available these days to players and the more serious fans in football.
Someday I hope the TV announcers and producers wake up to this wonderful dynamic little battle going on beneath their eyes and cover it better. Today instead we get Brent Musburger or some other person droning on between plays and endless shots of the sideline or the QB's grill right at the snap. Sometimes they don't even bother to show the snap of the ball on some plays. It would be nice if we could someday get better viewing angles for games on TV. The normal narrow angle that focuses in on the line of scrimmage is good for excitement but not much else. In breaking down the film after the game coaches normally rely upon the high overhead shot from the press box and the high end zone shot from behind the line of scrimmage. With these angles and some better commentary all football fans could learn more and appreciate more of the subtle complexities behind each and every play on the field. I for one would even pay for it!