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Summer School 2020: Cover 4 defense — what it is, and how to beat it

We continue breaking down defensive coverage schemes

NFL Combine - Day 2

A common zone coverage that focuses on eliminating the deep portion of the field is Cover 4. Also known as quarters coverage, Cover 4 has four deep zones, typically two corners and two safeties, splitting a fourth of the deep portions of the field. The two safeties are in the middle of the field, while the corners take the quarter of the field to their side.

The safeties will read their run/pass keys, but against the pass they’re responsible for watching the release of the No. 2 (second-closest to the outside) receiver, especially in Cover 4 press where the corners really need to bail back. Corners typically align about 9 yards off the ball, while the safeties are on the hashes at a depth of about 14 yards pre-snap. Corners are typically aligned head up with outside leverage, peeking inside and forcing receivers that direction. Underneath the four deep zones are three zone defenders who stretch the entire width of the field, so the defense is susceptible to underneath throws; since that’s the case, Cover 4 is usually run against offenses that need a big gain.

This is a base Cover 4 defense out of a 4-3 above. The coverage would mostly be run out of nickel/dime sub-packages. The close alignment of the four deep players allow the coverage to be disguised very well with other zone, and even man, coverages. As you can tell, the linebackers are spread pretty thin and the flats are vulnerable. Corners can line up in press and bail at the snap, confusing cornerbacks with a disguised Cover 2. The corner’s presence could prevent the quick flat throws, but the corner must be athletic enough to drop to his deep responsibility, too.

Another strength of quarters coverage comes with cohesion between the two deep players on each side of the field. A corner and safety on the same side of the field can work with one another against certain route combinations to their side (rules can be based on receivers stem and the direction of the combination). This type of teamwork can allow those two players to trust each other’s positioning and provides more flexibility to the back end coverage (bracket/inside out combinations). This is important against uneven sets, BUNCH, or TRIPS formations where the covering players can make a “box” type call where the coverage has more man principles, while still executing zone coverage initially (if the No. 1 goes outside the corner takes him, if he goes inside the safety, etc.).

Coverage vulnerabilities

The outside flat zones are open for business against a Cover 4 defense, so any type of hitch or speed out will be very hard to defend, if the corners bail to their responsibilities at the snap. As I stated earlier, corners can sink down and bail, to make the quick game (three-step or fewer) of an offense hesitate, but that leaves the defense vulnerable to double moves; an adjustment any adept offensive coordinator would make against a defense biting down.

The underneath defender to the right side is way too far away to cover the out route from the No. 1 receiver, so an offense can keep taking what the defense gives them until they attempt to cheat the corner closer to the line of scrimmage. That’s when you hit the corner with a double move while his momentum is closing downhill on what he expects is another out route. This is an excellent way to play chess against a Cover 4 defense. The stick route by the No. 2 wide receiver on that side will hold the linebacker, while the streak/post occupies the other three deep defenders.

There’s a copious amount of strain on the underneath defenders to the curl/flat and quick hitches from a 2x2 set would basically be a gimme for the offense.

The outside underneath defender’s zone becomes flooded by the mirrored concept and it becomes a 4-on-2 advantage for the offense. Football is all about capitalizing on numbers and space, and a Cover 4 defense provides ample space in the flat and the underneath portions of the field. The three defenders struggle to combat certain coverages and receivers can easily find gigantic voids in the underneath zone. This is one reason why a Cover 4 defense is a huge risk in manageable first- and second-down situations; the back end players need to be cheating upwards in some manner. Play action passes are deadly against these deep defenders who do cheat up to stop the run, and this is one reason why we see blown coverages when Cover 4 deep players are also aggressive against the run.

Again, four passing routes in the underneath zones, with only three defenders. The No. 2 to the right clears out the strong safety and may garner the attention from the free safety, while both outside receivers run snag routes in the holes and before said safeties. If the linebacker to the right watches the No. 1 receiver then the running back’s flare route will be wide open with space. The No. 2 receiver’s speed out will garner the attention of the near-side linebacker to the left, which opens the throwing window to the snag that goes over the top of his original position. There are many three-step route combinations (slant/flat, curl/flat, speed-out/curl from wider splits, tare route from a 3x1, spacing concepts, double slants, etc.) that would take advantage of the underneath defenders, but that’s not the only thing susceptible in a Cover 4 defense.

The dagger concept to the right side is an excellent way to cause problems for deep defenders. Deep defenders become manipulated pretty easily with clear out routes, followed by some kind of replacement route. None are more common than the dagger (clearout/dig) combination that you see above to the right side of the formation. The No. 2’s streak commands the strong safety’s attention and the underneath drag (which is supposed to be walled off by the MLB) from the backside brings the attention of the underneath defenders towards the line of scrimmage. This opens up a huge void where the strong safety is supposed to be and quarterbacks usually hit the dig in stride here, especially with the free safety taking the No. 2 receiver to the backside deep. This same type of scenario can happen with a deep horizontal cross concept.

Both the deep middle of the field defenders are put into conflict here. A defense with good communication would force the left side cornerback to switch his assignment once the No. 1 receiver to that side breaks inward. If there’s a hiccup there, the free safety is forced to take the No. 2’s streak, which opens up the void for the right side cross to come into the zone manned by the free safety. If the strong safety bits on the right side cross, then the left side cross will come into his zone. The quick snag, or OTB route, by the right side No. 2 receiver keeps the linebacker’s depth in check with a six-man protection. Cohesive defenses can handle this concept, but one mistake will lead to a blown coverage.

Much like the dagger concept, the Mills concept (also called a pin route) opens up voids in a Cover 4 defense, too. It’s another excellent way to engineer openings and put deep defenders into conflict. In the specific case above, the Mills concept is to the right and it puts stress on the strong safety. To the left, there’s an under route from the No. 1, with a streak to occupy the free safety, which opens up more room for the dig to the other side. The under route also demands the attention of at least two underneath defenders.

Scissors concept is a great way to confuse backend coverages, as well. This is most commonly run from a tight split or a stack, so the 7 route has more room to operate towards the sideline. To the left side, the No. 2 receiver uses a dino stem (hard inside route sell) to sell a deep post. This will command the attention of the free safety, but more importantly, it would focus the nearside corner’s attention on the outside receiver. The No. 2 then turns his route into a POCO (post-corner) route, while the No. 1 runs a slightly deeper post. The free safety and corner must be in line with what’s going on and if one of them makes the wrong decision then it’s a blown coverage and a huge gain for the offense. The double move by the No. 2 really confuses the assignments. On the right side, there’s a smash combo, which is a simple high-low where the inside receiver runs a 7 route and the outside receiver runs a quick hitch. The hitch may be open, depending on the speed of the linebacker, but the goal is to get the corner to jump the hitch, opening up the deep 7 route. Since there are two defenders in the area, it’s not technically a high-low, which would be much easier to do from a 3x1 set, but Cover 4 can certainly be high-lowed (typically Cover 4’s backside receiver plays man to man in 3x1 sets, so the variation defense can roll its coverage towards the three-receiver side. If the backside receiver is in a reduced split, the safety to that side can cheat up in hopes of either breaking up or intercepting any quick throws over the middle to the backside).

To the right side, the linebacker is being high-lowed by the out route and the running back’s flare; defender’s are typically taught to eliminate the most dangerous route, so he should drop to the out, but he’s in conflict and will be wrong one way or another. The clear out to that side helps take the corner deep, while the out route to the other side is run at a depth to where the corner will be unable to guard it, since he’s on the streak. The linebacker would have to notice and drop deeper than usual, which is a tough task given the amount of space he has to cover from the hash to the sideline. We focused a lot on how to manipulate the deep middle of the field, but the outsides are vulnerable, too, just like we see above.

The play above, run from a 2x2 set again, is a way to manipulate both an inside deep defender and an outside one, but an offense must have good protection to allow all of this to develop. To the right, the offense runs a sail pattern which features a streak from the outside receiver and a 7 route from the inside one. This concept puts both the corner and the nearside linebacker in conflict; the corner has to take the streak which opens up a huge void for the 7 that can’t be covered by the linebacker, because of the distance and the flare route from the running back. On the opposite side, the strong safety is put into conflict. The No. 2 receiver has to run past the depth of the nearside linebacker, directly at the strong safety and sit at about 13 yards in hopes that the safety bites down on the route, which would allow for the deep post to be wide open behind him. The right side combination is called a fish concept because it baits the deep player and it acts as another high-low read for the quarterback. These combinations are very common in the NFL and against defenses’ like the Cover 4.

As alluded to earlier, play action passes can be deadly against aggressive Cover 4 teams and the yankee concept is one of the passing combinations that can leave deep defenders scrambling. Naked bootleg rollaways are also excellent ways to create chaos for the deep defenders.

The quarterback would roll right with the offensive line moving the pocket in that direction. The play action would suck the defense close to the line of scrimmage and then the quarterback would have a two-tiered read. The lone receiver to the right would be 1-on-1 against the corner, which is fine, but the quarterback is reading the free safety; the outside receiver to that side will have inside leverage against the corner and the free safety is going to have to take either the deep post or the intermediate post, which is probably the one he’d be baited into selecting. If that happens, the deep post should have plenty of space with a lot of leverage on the outside cornerback. This route concept can be made into a three-tier read as well; put the tight end on the opposite side, hinge the left tackle and make the running back slide his protection to the right. The tight end would then run a quick slant behind the linebackers. This would give the quarterback a three-tier read, putting the defense into conflict.

The underneath portions of the field are vulnerable against Cover 4 defenses. Three-step route combinations and quick screens are very advantageous ways for the offense to gain an advantage against the defense in a Cover 4. Both underneath and deep zone defenders are susceptible to being manipulated either through route combinations drawing defenders to desired locations or just by high-lowing certain defenders. Levels concepts and the Texas concept, with a tight end occupying the middle linebacker, are also excellent ways to attack the middle of the field. Double moves also prove to be dangerous against the coverage, so the deep coverage has to be in sync with one another to effectively guard concepts like a scissors combination. Cover 4 is still a solid coverage against 2x2 sets where the offense needs to gain a lot of yardage. Defenses have tons of calls mixed into their playbook that highlight rules to abide by in certain situations. Since the NFL runs a lot more 3x1 sets, Cover 6 has been more prevalent in the last decade (Cover 6 is a mix between Cover 2 and Cover 4, also known as quarter quarter half), although Cover 4 can have success against these sets as well, especially if the defense has the right rules in place.