Football Fundamentals: Cover 4 Defense "Coverage"

At its most basic, Cover 4 plays as a four deep, three under defense; and at its most aggressive, it plays almost identically to a tight Cover 0. To the average fan, Cover 4 may sound like a passive, prevent-type defense, while to the more nuanced fan, it may seem like an aggressive coverage that can bring 9 defenders into the box. The truth is that it is all those things and more. One of the greatest powers of the Cover 4 is its ability to adjust, the intricacies, and tweaks that can be made to the same look to both confuse the offense, and remain fundamentally sound. In this article, we’re going to look at the basic elements of coverage in a Cover 4 defense.

The Basics

Strengths	Weakness	How to Defeat
Four-Deep Coverage	Flat Coverage	Out routes from #2
9-Man Box (Safety Run Support)	Overload Underneath Zones	Flood/Overload Concepts
Bracket coverage on #1	Safeties in run/pass conflict	Scissors Concept
Outside Coverage Options (Tight/Soft)	DBs on an island	Double Post/Mills Concept
Wrinkles to Bait Throws	Pulling DBs out of Zones, forcing poor leverage	Mesh Concepts/ Underneath Rubs
Simplified LB Coverage	Rub routes	Play Action
Adaptable to any offensive set	Flood Concepts	WR Screens

Cover 4 is a combination scheme that employs both zone concepts and man concepts. In this way, it utilizes “pattern matching” to its advantage. This makes it a bit more complex to execute, but also a little bit more adaptable to offensive sets and concepts. Also known as “Quarters” (we won’t call it that, as we’ll describe in a bit), there are several ways of adjusting the coverage, adjusting the position of the LBs, and altering eye position and coverage technique. The most basic versions of Cover 4 are going to be "Quarters", "MOD", and "MEG" as described below. The remaining defenses are wrinkles to take advantage of how defenses are attempting to defeat the nominal coverages.

Here's a couple examples of alignment, the first showing a press alignment and an option on how to cover some of the receiver splits:

The second shows off coverage

Standard Underneath Coverage

Underneath, the OLBs are responsible from working inside-out, from the edge of the box to the flat, protecting Hook, to Curl, to Out/Flat. The MIKE is responsible middle/hook. They also have the responsibility of “walling off” anything that comes underneath. This means that if a receiver tries to work across the middle of the field, that the MIKE should essentially block him from being able to cross the field; by walling off, he interrupts the offense’s timing, prevents the offense from flooding a side of the field underneath, and allows the MIKE to break on anything immediately in the direction the receiver is coming from.

The underneath coverage will change a little bit based on the coverage adjustment, so just be aware of that, though I may not explain that fully.

Quarters

We’re going to start with what I define as quarters, that being a true 4 deep zone concept. This isn’t prevent, this isn’t automatically stay deeper than the deepest and play passive, but it is a bit of a safer shell coverage.

On the back end, the CBs are responsible for the outside ¼ of the fields and play with outside leverage over the #1, while the safeties will take the ¼ of the width of the field in the middle, meaning each DB is responsible for a quarter of the width of the field deep. CBs funnel to the safeties and safeties funnel to the CBs with their leverage.

Both the Safeties and the CB read through #2 or the EMOL and to the QB. Nothing changes for the CB with the action of the #2, what changes for the CB is if the safety fills forward in run support. If the safety comes forward, the CB needs to be more cognizant of the #2 and potentially split the difference with his zone (essentially a deep half). More to the point, is that the CB needs to scan the field, looking for crossers coming from the other side of the field, or otherwise sticking with the #1 on his side.

The safety reads through the #2 to determine if he can double, or bracket, the #1. If #2 goes vertical, the safety must respect his zone. If #2 stays short, the safety can work to maintain inside leverage on the #1 (unless he crosses).

Strengths: The strengths of this is that any deep route concept, including deep rubs, are covered, and the DBs don't have to be worried about being "out-athleted" by having to chase defenders around the field. Likewise, double moves or wheel routes are covered without having to have great eye discipline. Furthermore, safeties can afford to be aggressive in run support because of the CB automatically playing deep coverage.

Weakness: The biggest weakness is the underneath zones. Quick outs or mesh concepts can overload underneath coverage, which is spread thin. Play action will often suck up the safety, potentially leaving the CB alone against two verticals.

Man Only Deep (MOD)

The classic example of Cover 4. This is a 4 deep zone that turns into man coverage on deep routes.

The CB is going to read #1 through the play. If #1 goes vertical, the CB is going to match up with him in man-to-man. If #1 runs a short route (underneath 5-7 yards), the CB will sink beneath any deep route from #2.

The safety is going to read #2 to #1. If #2 goes vertical (5-9 yards), again, the safety has him in man-to-man coverage. If the #2 stays short, the OLB will take responsibility for the coverage and the safety will double #1.

Strengths: This has four defenders deep regardless of the offensive route structure. Man coverage deep allows for tighter coverage in the secondary and doesn't allow the offense to pull defenders out of their zone. This coverage allows a single vertical route to be bracketed by the CB and Safety (assuming the other remains shallow).

Weakness: Underneath coverage is still susceptible to being overloaded. Downfield rub routes can get DBs caught in the wash. Double moves or wheel routes can result in DBs bracketing the first receiver to get vertical.

Note: To a single receiver side, this may be called "Cone" in "Sabanese". What this means, is that any vertical route from the single side WR will result bracket coverage between the CB and Safety. But if the single WR goes shallow, both DBs will play their deep quarters coverage.

Also note that MOD can be run from a press alignment or off alignment. Saban separates the two calls by saying "Box" when he wants his CB in an off alignment.

Man Everywhere he Goes (MEG)

This is the more modern variant of Cover 4. It is often associated (though not necessarily correctly) with press coverage on the outside.

The CB is going to play the #1 in straight man-to-man coverage, anywhere he goes. If he stays short, the CB stays with him. If #1 runs deep, the CB stays with him. There are some exceptions to the rule, such as if the #1 immediately stems inside, such as on a crossing route, in which case the CB will exchange assignments and cover #2.

The safeties check #2 to #1. Again, if #2 goes vertical (5-7 yards), the safety will pick him up in man coverage. If the #2 stays underneath, the safety will look to double #1.

Strengths: Man coverage on #1 helps prevent underneath zones from being overloaded, takes away the quick hitch to the outside, allows the OLBs to play tighter into the box, focuses coverage on the best receivers, and allows the defense to run tight, man coverage on deep routes.

Weakness: Deep outside routes, such as fades, often see the CB alone on an island without much over the top help. Downfield rub routes can be effective against man coverage. The safety is often isolated against a safety with an in/out release option on vertical routes because the #1 can remain shallow. 

2-Read

2-Read (also known at "Trap", "Clamp", "Palms", or "Rolex") is a split between Cover 2 and Cover 4.

In this case the CB is reading through #2. If #2 goes vertical (~7 yards), the CB drops into a deep quarter coverage and essentially plays quarters. If #2 stays short, the CB plays him outside-in (funneling into the LBs) and looks to jump any outward breaking route.

The safety also reads #2. If #2 goes vertical, the safety is responsible for playing a middle ¼ zone, similar to quarters (inside leverage). If #2 stays short, the safety must adjust his drop to play a deep half, because he is now responsible for having to cover #1 running down the sideline, similar to Cover 2.

Strengths: Jumps outward routes from #2, which is a common quarters beater. Helps prevent underneath zones from being overwhelmed by having the CB jump #2. Plays like Cover 2 against shorter route concepts, but still has Cover 4 adaptability against verticals.

Weakness: The safety has to get outside over top #1 in the event that #2 runs an out route (pole concept). Cover 2 beaters can be effective (smash, pole, post-wheel).

Note: Teams will play this a bit differently, or can have different calls. For instance, in Clamp, the CB is playing MOD against #1 unless #2 goes out early in his route. This means, if #1 runs a hitch, the CB is still playing deep 1/4 anticipating smash and the LB/Ni is responsible for covering the hitch. In this way, you can differentiate 2-Trap Cover 2 from the quarters variant (which Saban does by calling "Cut").

Robber

Robber is going to see the Safety playing a "Robber" technique (and underneath zone) in certain circumstances. Here, the read is #2 to #1. If #2 runs a shallow route that breaks inside, the safety will jump the route. If #2 runs a shallow route that doesn't break in, the safety will check #1 to see if he's breaking inside. If #1 is breaking inside, the safety will "Rob" the coverage, otherwise, he'll break on #2. If #2 goes vertical, the safety will play his standard middle 1/4 zone.

The CB, for his part, has his eyes through #2 initially. If #2 runs deep, the CB will play his outside 1/4 Zone. If #2 runs shallow, the CB will be responsible for defender his half of the field deep (typically, this will essentially mean manning up #1, but he can't get beat deep).

The OLBs must get outside in Robber coverage. The safety is jumping any inward breaking route, you want the QB to see the OLB buzzing outside quickly to bait that throw.

Strengths: Baits inside throw for safety coming down hill. Helps mitigate offense from overloading underneath zones. Puts safety in run support inside the box. Zone deep prevents downfield rub routes, while robber threatens to bait inward breaking underneath rub routes.

Weakness: Pulls the OLB out of the box immediately at the snap. Inward breaking deep routes from #1 paired with outward breaking routes from the #2. CB potentially isolated deep without advantageous leverage (outside leverage without safety support). Wheel routes can bait "robber" and get behind defense.

Thumbs

The idea of thumbs is to bracket #1 is #2 doesn't go vertical. In this way, the safety is playing everything deep, inside-out, and if the #2 runs a shallow route, then the safety can jump whatever route #1 is running.

Because of the safety's responsibility, the CB is going to play a little softer on the outside. Any double move, he's responsible for not getting beat deep, because the safety is working to jump the underneath route. The method of play for the CB is really the same as quarters coverage.

Strengths: Brackets #1 any time #2 doesn't go vertical. 4-deep zones against verticals allow it to defend downfield rub routes. Can jump routes to the outside receiver.

Weakness: Doesn't allow the safety to play run support as quickly. OLB matched up on a slot receiver underneath without over the top help. Double moves by slot can get safety out of position and prevent him from playing #2 vertical from outside-in.

Switch

Switch is another way of incorporating a Cover 3 or Cover 6 scheme into the defense. The concept is pretty simple, if #2 runs an out route, the safety jumps it as if playing Sky (teams will play a hitch from a slot receiver differently, some will jump it, and some will stay back). If anything else happens, the safety is playing his middle 1/4 zone.

For the CB, he needs to read through the #2. If #2 runs an out, he is responsible for the deep 1/2, which is typically man coverage vs #1. Otherwise, he's playing the outside 1/4 zone. Note also that if #2 runs an out, the LB/Apex should be thinking about robbing any inward route from #1 (slant/dig/ curl). The safety is working down over-top of #2, so the LB doesn't need to necessarily maintain contact, and can sag off and underneath #1.

Strengths: Plays like Cover 3 with sky support against any outward breaking route from #2. Very effective against bubble screens. 4 deep zones help defend downfield rub routes. Allows OLBs to play tighter inside the box.

Weakness: Underneath zones can be overloaded as long as #2 doesn't run outward breaking route. Any deep inward breaking route from #1 paired with out route from #2. Sucks the safety out of the box for run support. Wheel routes.

Why Use Adjustments
Brophy says it well in his article on Saban's Cover 7 (his version of cover 4)

Why would you use [these adjustments]? Why wouldn’t you just hang back in standard quarters? Because the common weakness of quarters in the perimeter distance for the OLB to respond to. By modifying how the #1 receiver [edit: or #2 in the case of Rolex] is played, you can remain in the same coverage with a minor tweak on the (standard) routes that will be used to attack quarters coverage (underneath). With a corner locking down the #1 receiver, it will become a 2-on-1 match between the OLB and deep safety.

Etc.
We haven't yet touched on how quarters adjusts to 3x1 sets, that will be the topic of a future post. Similarly, we have left off bracket coverages and 2-Man from this article. Both can be folded into your quarters coverage playbook or can be treated similarly. Both can work from a 2-high shell.

Conclusions

There are more combinations of coverage that can be discussed, including hybrid coverages (hybrid Cover 4 types, hybrid Cover 2/4, hybrid Cover 0/4, trips adjustments, knob adjustments, underneath coverage adjustments). A lot of Cover 0 also play similarly to Cover 4 (think about MEG, and against vertical routes, how it essentially turns into a form of Cover 0). There is also the topic of leverage and cushion, including at the CB, Safety, and OLB position. In the next post, we’re going to focus on the latter topic of leverage and cushion, before we get into more detailed adjustments and hybrid coverages.

Etc.
Cover 4 Diagram
MSU Cover 4 Basics
Cover 4 Safety Play
Breakdown Sports Cover 4 Tag
2-Read Coverage Breakdown
Matt Bowen Cover 4 Intro
Rolex Coverage
Nick Saban's Cover 7 (his terminology for Cover 4)