Bench Points Summer Workouts: Defensive Secondary Shells

So, I got about 3 paragraphs into this week’s serial post about timing rules when I realized that I was boring myself. It was horrible. It literally caused me to take a nap. I won’t subject you to that. You’re welcome. I think we’ve covered enough rule nuances in talking about Pass Interference and Catches in prior weeks. Let’s move on to discuss basic secondary coverages and packages. The elements of offensive schemes are certainly complex and will be discussed in upcoming articles, but the defense does not get enough credit for its complexity. The defense is allowed to be more fluid in nature and more dynamic than the offense. The offense has to set, the defense does not. The offense has to have seven men on the line of scrimmage, the defense does not. Offensive plays have extensive governing rules; that isn’t the case for the defense. We’ll start out discussing the main coverage packages and then talk about some of the specialist packages comprising the defensive secondary. If you suck at Madden like I do, then you do not give much credence to your defensive playcalling–truth be told, I don’t give much thought to my offensive playcalling either, but that’s a story for another time. In football, defensive schemes arguably begin with the coverage; there are exceptions, of course, but generally speaking, how you cover the eligible receivers is what determines the rest of the defensive playcall. Defense is naturally reactive. It’s predicated on reading the offensive play and reacting in time to beat the ballcarrier or receiver to a spot in space and foil the plan. On pass plays, this takes the form of the secondary coverage. There are basically four coverages–3 zone, 1 man. And, although man coverage has two versions, the coverage is not quite different enough to consider it separate. Let’s go through them.

Cover 0/1 – “Man to Man”

We’ll start with the easiest coverage to grasp, and that is man to man coverage. This coverage assigns defensive backs to specific receivers and tasks them with following that receiver around the field. You’ll recognize this formation when the offense brings a man in motion and a defensive player follows him across the formation. Cover 0/1 provides the rest of the defense with maximum flexibility due to only needing one guy in coverage per receiver. This is also the most vulnerable coverage to mismatches if the defensive backs lack the ability to cover their receiver.

As mentioned before, Cover 0/1 is very much like two distinct schemes, but they are not dissimilar enough to really be separately analyzed. As a general rule, the number assigned to the coverage refers to the number of deep backs covering zones. Cover 0 is all man to man, with any extra DBs involved in either a double team or other defensive endeavor–there is no one covering a deep zone at all. Cover 1 is man to man with the deepest safety covering a deep zone–usually, this results on a double team on the deepest receiver between the numbers. The safety may cover a deep sideline route, but it’s unreasonable to expect the free safety to cover sideline to sideline all the time, but it does happen periodically.

Cover 1 is easily recognizable due to the free safety on an island about 25 yards off the ball. Cover 0 is equally easy to see as there is nobody deep and all the defensive backs are marked up on their receiver.

Cover 2

Sticking with the trend of the coverage number, Cover 2 describes two deep safeties that divide the deep secondary into halves. Cover 2 is considered a zone coverage, although it can be complex enough to have elements of man coverage comprising the final scheme. Typically, however, the entire coverage unit is assigned various zones and there is not a man coverage component. The middle distances are covered by the linebackers while the flats and sideline zones are covered by the cornerbacks. Cover 2 is a dated coverage that is easy to scheme around for offenses, but is a sound defensive alignment when the defense cannot cover receivers one on one.

With Cover 2, the deep sides are covered by the two deep safeties. However, since traditional cover 2 splits the defensive backs to either sideline, the defense has a vulnerability to a receiver running straight down the middle of the deep zone–which is usually the very common post route. To combat this, cover 2 has various alignments that assist in covering the deep middle. Each team has a different set of terms for them, but the idea is the same–common terms for this special cover 2 are “sky” and “cloud.” The two deep safeties take over/under positions instead of splitting to either side. This has its own vulnerability down the deep sidelines–not unlike Cover 1–but no defense is watertight. In this writer’s opinion, straight cover 2 is dated and too easy to defeat for advanced offenses.

Cover 2 is easy to recognize as the two deep backs–free safety and strong safety–are found 20-25 yards off the ball.

Cover 3

Honestly, Cover 3 is stupid as a pass coverage. It’s an afterthought defensive coverage shell that complements a run-stopping defensive alignment. Two corners and a free safety divide the deep field into thirds. This is assuredly a zone coverage and, with three deep backs, it shuts down deep pass plays, but gives up nearly any short to middle distance pass. Not great unless the offense is staring at 3rd and Texas and you want to send the strong safety on a blitz. Cover 3 does a decent job handling most deep plays; although there are thin areas around the hash marks in Cover 3, these are seldom exploited as 3 defensive backs are fast enough to cover the width of the field.

The coverage does have the benefit of deception and allows defenses to “load the box” without creating asymmetry in the pass coverage. The lone deep free safety allows the coverage to appear to be Cover 1. Unless the offense has the presence of mind to motion a receiver across the formation, this has the chance to trick the opposing quarterback. Additionally, bringing pressure in other coverages has the potential to expose a major vulnerability if the pressure does not yield the desired result.

Cover 3 can be recognized during motion across the formation–if no one on the defense follows, but it looks like Cover 1, then it’s probably Cover 3. Cornerbacks in Cover 3 typically “cheat deep,” meaning they start a decent distance off the ball. If the defensive shell is in Cover 1, the corners tend to be closer to the ball. So, if the corners are deep and there is a sole safety, it’s probably Cover 3.

Cover 4

The “quarters” shell is hallmarked by the 2 corners and the 2 safeties divvying up the deep zone into fourths. It is also called the Prevent defense as it prevents most any deep shenanigans that an offense can come up with. However, deploying 4 backs to the deep zone leaves a lot open underneath. This defensive scheme often mandates stealing a player from either the defensive line or the linebacker corps.

Now, obviously, a 300 pound defensive tackle isn’t going to cover Calvin Johnson on a Hail Mary play. So, the defense substitutes one or two defensive backs–the nickel and dime backs, respectively. These assist in pass-heavy offensive situations, like the 3rd and Texas situation mentioned above. Additionally, the Prevent is used by a team that is leading who hopes to bend, but not break when the opponent has the ball and is driving at the end of the game.

Cover 4 is recognizable if it looks like Cover 2 and no one follows a receiver across the formation. Additionally, the personnel package can give it away. If there are only 3 linemen or 2 linebackers, that tends to be a dead giveaway for a pass heavy defense like Cover 4. Again, it will look like ordinary Cover 2 if there is no motion, but the cornerbacks will again be cheating deep so that they can get to their responsibilities quickly. Cover 4 sucks for run stopping, so we usually see it in low clock or long yardage situations. Otherwise, it is far too vulnerable to a run or screen pass.

Cover 6

Cover 6 is a fantastic zone coverage, if you have the personnel to run it. Odds are, your team doesn’t. In order to properly field a Cover 6 unit, a team must commit to that scheme for years and recruit the proper players to run it. Cover 6 divides the field into weak and strong sides and biases a coverage based on strength. It’s called Cover 6 because it has elements of Cover 4 and Cover 2 put together–four plus two equals 6, don’t think about it too hard, coaches are just glorified PE teachers.

In this scheme, half the coverage looks like Cover 4–the strong safety and corner on one side drop into quarter coverage with the linebacker filling in underneath–and the other half looks like Cover 2–the free safety drops into a deep half. This coverage frees up the strong side corner to highlight a particular receiver at the cost of an outside linebacker, who is likely more of a defensive back than a linebacker anyway. Although this coverage has both strengths of Cover 2 and Cover 4, it also has both weaknesses and many “soft spots” for shorter pass plays, especially to the sideline.

Cover 6 can be recognized by looking at the backs. It’s going to appear like Cover 2 or Cover 4, but only one cornerback will be cheating deep. The other corner will likely be walked up to provide more of a man coverage feel to the strong side receiver. Cover 6 is used as a base pass coverage, but is weak against the run. Cover 6 defensive units may take up the alignment on shorter yardage plays, but the appearance may simply be a deception to disguise a completely different run stopping defensive scheme that has nothing to do with Cover 6.

This is very basic, and we could spend days going over the nuances of secondary shells. It is my hope that this is clear enough to understand and provides a sufficient picture of the coverages. When we get into the season, I plan to do a more in depth series about these alignments.

Keep in mind, though, defenses are intentionally meant to deceive and this is a very high level overview. The higher level of football you watch, the more complicated the shell schemes become. They’re meant to confuse quarterbacks who study defenses regularly. So, deciphering the defense presnap is challenging, but hopefully this illustrated a handful of tendencies so we know what to watch for.

Defense is hard.


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