Welcome to Football 101 presented by The Painted Lines! In this ongoing offseason series, I will be breaking down football concepts to help you better understand what you are watching on Sundays. Each article will take a deep dive into a specific component of the game. We will also be updating a cheat sheet throughout the series that you can bookmark or print out for quick reference on game days. You can also join our public discord to interact with our writers and podcasters and talk X’s and O’s.

If you have missed any of the previous articles of this series you can check them out below:

Without further adieu, let’s dive in!  Today we are going to take a look at our final and most complex defensive coverage: Cover 4

The Basics

Cover 4.jpg

Cover 4 is a zone coverage that relies on 2 safeties and 2 cornerbacks to cover the deep areas of the field and 3 linebackers/cornerbacks to cover the underneath portion of the field. Because it does not walk a safety down into the box, it is often more susceptible to running plays and thus play-action passing as well. Its standard deployment is called Cover 4 Quarters, or simply Quarters.

The biggest strength of Cover 4 is also the biggest detriment to writing an article about the basics of it: It is very complex and has the ability to adjust to nearly anything the offense can throw at it. It has many more coverage checks than we could possibly talk about in a concise way, so while our Cover 2 and Cover 3 primers covered about 95% of the adjustments you will see out of their deployments, this article will likely only cover about half of what you could see from Cover 4. It is an extremely complex defense and is very demanding on defensive backs to be able to make multiple reads and adjust on the fly.

Typically the cornerback will shade outside of the receiver to force an inside release (similar to cover 2). If the outside receiver runs a vertical route (typically defined as no break in the first 12-15 yards of the route) then the corner converts into man coverage on the receiver. If the route breaks before that 12-15 yard mark then the cornerback sinks into a deep quarter zone.

The safety has the same responsibility for the #2 receiver (typically a slot receiver or a tight end) and will cover him if he goes vertical. If the #2 receiver does not go vertical the safety will convert to man coverage on the #1 receiver resulting in a double team if he went vertical. This technique allows teams to bracket the primary receiving threat with 2 defenders without sacrificing their deep coverage.

This coverage also allows safeties to be very aggressive against the run, knowing that if they bite on play-action they still have corners covering deep.

What is the Weakness of Cover 4?

The primary weakness of Cover 4 is the underneath zones. Cover 3 puts 4 defenders underneath and Cover 2 puts 5 defenders underneath while Cover 4 only leaves 3 players to cover the short to intermediate portions of the field. On top of that, play-action passes will pull safeties to the line of scrimmage and opens up areas down the middle of the field to be defended by the cornerbacks.



The Pin (post-in) or Mills concept is the most commonly used Cover 4 beater in the NFL.  The concept calls for the #2 receiver to run an in route deep enough that the safety converts to man coverage on him (past the 12-yard mark).  This leaves the cornerback in a precarious situation where he has outside leverage on a receiver who is running an in-breaking route without safety help over the top.  Against a speedy receiver, this can result in a huge play or a touchdown for the offense.



A scissors concept is also deadly to Cover 4. This concept sends both receivers vertical and forces conversion into man coverage before crossing one another. This puts the cornerback in a situation where he is outside leverage against an in-breaking route similar to the Pin/Mills concept, but it also puts the safety in a similar situation having to chase an out-breaking route.



Coverage Checks

Cover 4 Zorro

Cover 4 Zorro is a coverage check that defenses will run against compressed sets (when the receivers are closer to the ball instead of out wide.) These reduced splits often indicate that the offense will try a Scissors concept. Zorro plays just like Cover 4 Quarters except that if the receivers both run vertically and then cross each other like in a scissors concept, the corner and safety will exchange coverage responsibilities. The cornerback will take the out-breaking route in man-to-man coverage (the corner route in scissors) and the safety will take the in-breaking route (the post route in scissors).

Cover 4 Palms/2-Read

Cover 4 Palms (also known as 2-Read) is a hybrid Cover 2/Cover 4 zone. In this coverage, the inside receiver determines how the coverage works. If the inside receiver goes vertically then both the cornerback and safety drop into deep quarters, but he runs a short route the cornerback will aggressively attack one of the underneath routes and the safety is responsible for a deep half like in Cover 2.


You can see this play out in the above picture. The Y receiver runs a short, out-breaking route and the cornerback dives down to cover it. This leaves the safety to cover half of the field deep. On the other side of the field, the F receiver runs a vertical route so the corner and safety both drop into deep quarters.

This coverage check allows the defense to better cover the underneath routes that have the potential to overwhelm Cover 4 but relies on a rangy safety to be able to get all the way to the sideline and cover a vertical from the outside receiver.

Cover 4 Lock

Every coverage check that we have looked at so far assumes that the offense is in a 2 by 2 set (2 receivers on each side of the formation. If the offense comes out in a 3 by 1 set it changes everything for the defense. In this situation, the most common coverage check is Cover 4 Lock.


In this example, the cornerback on the left side of the field will automatically convert to man coverage on the X receiver no matter what route he runs. This allows the safety on the left side of the field to work to the middle (similar to a Cover 3 middle third zone) to help with passes to the Y receiver up the seam while the safety on the right side pushes more towards the sideline to split between the H and Y receiver.

Cover 6

Another hybrid coverage that teams can play is called Cover 6.  Cover 6 is basically Cover 4 defense on one side of the field and Cover 2 on the other side.  It gets its name because 4 + 2 = 6.  Look at that, your math teacher was right all along: math was important!  Cover 6 defense can also be called quarter, quarter half.  Cover 6 typically plays Cover 2 to the short side of the field and cover 4 to the wide side of the field.  This deployment is often used against 3×1 sets when the single receiver is on the short side of the field.

Cover 4 is an incredibly complex and versatile defense that requires safeties who can stick with receivers in man coverage and can quickly diagnose route combinations and make coverage checks. It is very adaptable and has the ability to confuse opposing quarterbacks, but at the same time has the ability to confuse defenders as well and give up huge plays if everyone isn’t on the same page. Typically you will see teams run Cover 4 more heavily against teams with an elite WR1 for its ability to bracket that receiver easily at the expense of underneath coverage.

That concludes our primer on cover 4 defenses. Don’t forget to go back and check out our article on coverage shells if you missed that and click on over to the cheat sheet if you want to review the strengths and weaknesses of different alignments. The links for both are at the top of the page.  Keep it tuned to the Painted Lines for our Football 101 series and let us know if there is something, in particular, you would like us to cover.  Next week we will be back to talk about personnel groupings and the offense’s ability to dictate defensive personnel packages.