Ever wonder where to start when learning how to identify pass defenses when watching film? We did. So Dave Archibald wrote an incredibly helpful primer on identifying pass defenses. Below, Dave takes you step by step through his process on how to figure out what coverage the defense is using on a given play.
“Coverage check, you degenerates.”
The request is usually phrased a little more politely (C’mon, Mark Schofield!), but it’s a common one around the Inside the Pylon Slack chat. One person watches a play, re-watches it, re-watches it again, and still he wonders: What exactly is that defense?
Diagnosing pass defenses has never been more difficult. Few teams run pure zone or pure man-to-man coverage shells, preferring hybrids that incorporate elements of both. Defensive coordinators love to disguise or roll coverage in an attempt to confuse opposing quarterbacks. Often, it works. And if modern pass coverages can fool NFL quarterbacks, is it any wonder they are tricky for the fan at home, or even the brilliant minds of my fellow Pyloneers?
Every defense has its own strengths and weaknesses, and passing attacks employ different strategies for throwing against the various coverages they see. Offensive coordinators design their game plans around the looks they expect, quarterbacks base their reads on the defense, and receivers often adjust their routes accordingly. Coaches and players have to be able to identify defenses ahead of time both during scouting, to know their opponent’s tendencies, and also in the game, to make the correct play calls and reads, so that the offense can function effectively. Accordingly, if the fan at home can learn the telltale signs of different coverages, along with their strengths and vulnerable points, he can gain a new appreciation for the strategic chess match underpinning every football game.
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This particular play Mark was asking about, from a game between Montana and South Dakota State, caused particular controversy around the ITP virtual office, so it’s an instructive example to show my process for identifying pass defenses – and why diagnosing the defense can be so difficult.
Step 1 – Count the Deep Safeties
You can cut the number of possible defenses roughly in half just by determining if there is one deep safety or two. “Deep” is a somewhat relative term, but a good guideline is more than 10-12 yards off the line of scrimmage. On the TV broadcast, deep safeties are often off-screen before the snap. Deep safeties are responsible for defending the receivers farthest downfield in their area, so as the play develops it’s not uncommon to see them covering deep routes 30, 40, 50 yards off the line of scrimmage.
One Deep Safety Look
The common “single high” defenses are Cover 1 and Cover 3. The deep safety is often called a “free safety” or “post defender,” while the other safety plays shallow as a “strong safety” or “box safety.” Cover 1 features man-to-man coverage underneath, while Cover 3 is a zone defense. Teams that run a lot of Cover 1 and Cover 3 defense generally have traditional notions of what a strong and free safety are. For instance, the Seattle Seahawks, famous for their Cover 3 scheme, sport rangy free safety Earl Thomas and heavy-hitting strong safety Kam Chancellor.
Single-high defenses provide help to cornerbacks in the middle of the field – most notably on post routes – but the corners are largely on their own for deep routes along the sidelines. If a team lacks cornerbacks that it can trust in coverage in addition to a free safety with range, it is hard to run single high schemes. With the right personnel on the back end, though, these schemes can pose big problems for offenses up front; putting the second safety in the box gives the defense options in defending underneath routes, providing run support, or blitzing.
Two Deep Safety Look
The common defenses with two deep safeties are Cover 2 Man (sometimes called Cover 5), Cover 2, and Cover 4. Cover 2 Man, as one might expect, is a man defense, Cover 2 is a zone defense, and Cover 4 is a zone defense with some man-to-man principles. The “split safeties” in these defenses don’t need to be quite as rangy as prototypical free safeties or lay the wood like classic strong safeties, but they must do some of everything. As deep defenders, they are still providing vital pass coverage on the back end, and since there’s no strong safety in the box, they must be quick to assist in run support. The cornerbacks have more help deep so they don’t need the top physical traits of single high corners, but they can sometimes have more run responsibilities, particularly in Cover 2.
From time to time, defenses will play with no deep safeties, which is known as Cover 0. This is generally an all-out blitz, where the defense is gambling they can get to the quarterback before he can connect on a long pass. A “Zero Blitz” that can’t get home is often a recipe for a long touchdown. Cover 0 always features man-to-man coverage underneath.
The distinction between one deep safety and two deep safeties is so critical that offenses will often change or “sight adjust” the route that receivers run based on how the safeties are positioned. They will read if there is a post defender in the middle of the field (i.e., one deep safety), or if the deep middle is open between two deep safeties. A wideout might run a post against a “Middle of the Field Open” (MOFO) defense and a dig against a “Middle of the Field Closed” (MOFC) defense, or a tight end might run up the seam against a MOFO look and sit down against a MOFC look.
The fan at home or player on the field can often read the number of safeties pre-snap, but defensive coordinators get paid to make things more difficult than that. One of their favorite tactics is to “roll coverage” pre-snap, showing one coverage and then shifting into another at the last moment:
Commonly, that involves dropping a strong safety into a deep zone, creating a two deep safety look, or having a deep safety rotate into the box, creating a one deep safety look. The Montana play is such an example: The defense shows two deep safeties before the snap, only to have the safety towards the top of the screen roll towards the line of scrimmage to create a one deep safety look.
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Some might argue that because the safety to the field side doesn’t move until after the snap, this is a two-high look and the safety is reading the run play. However, the safety to the boundary side shifts towards the middle of the field at the snap, establishing a deep position as the post defender. This appears to be a designed roll from a two deep safety look to a single high coverage.
Note: As offenses get near the end zone, there is not enough space for defenses to be concerned with defending the deep pass, and the “count the deep safeties” heuristic is less useful. Generally the safeties will lurk in shallow areas or cover skill players man-to-man. Against jumbo goal line sets, a team might have only one safety on the field, or even none.
Step 2 – Check the Outside Cornerbacks
Having roughly classed the defense as one deep safety or two deep safety defense, the next thing to do is break it down into a man-to-man or zone defense. The simplest way to do this is to watch the hips of the outside cornerbacks. If it is a zone defense, he will want to face the quarterback, and so he will execute a zone turn and flip his hips towards the quarterback as the receiver approaches. If it is a man-to-man defense, he will execute a man turn as the receiver approaches, facing away from the quarterback and towards his man. Cyrus Jones (#5) of Alabama demonstrates the difference in consecutive plays:
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If you see a zone turn, that is a pretty reliable indicator of zone defense. The number one thing a man-to-man defender cannot do is “lose” his man, and a professional receiver that sees a cornerback looking the other way before the ball is thrown can make himself lost in a hurry. Executing a zone turn in man-to-man coverage is therefore a risky maneuver.
A man turn, however, is not as reliable an indicator. Seattle did not invent the idea of using man-to-man cornerback techniques in zone coverage, but they have sure made it popular. Teams around the league often have their outside corners press the receivers and execute a man turn before defending their zone area. This disguises the coverage and also helps defend the short pass, traditionally a weakness of zone coverages. Many teams coach their outside cornerbacks to use man turns in Cover 4 as well, as they cannot count on safety help to the inside and therefore must expect to cover the wideout man-to-man.
As with the middle of the field open/closed designation, offenses will often adjust receiver routes based on whether they read man-to-man or zone coverage. An outside receiver facing press coverage, for instance, will often adjust a vertical route to a fade or fly pattern, hoping to beat the cornerback’s press for a long gain up the sideline. Some offenses love to have their slot receivers run option routes where they can break in any of four directions based on whether they see zone or man coverage and whether the defender is shading to the inside or outside. The New England Patriots, for example, love to throw to their slot receivers on these option routes. For purposes of these adjustments, the receiver generally looks at whether the man in front of him is playing man or zone technique, not whether the entire defense is man or zone.
The quarterback doesn’t have the luxury of focusing on just one defender, and neither does an analyst trying to identify the pass coverage. The Montana clip is a great example of how different defenders can suggest different coverages:
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The outside cornerback on the short side of the field – the boundary corner – executes a man turn. The field corner at the top of the screen, however, opens towards the middle of the field. That isn’t necessarily a zone turn, however, as the receiver is running a shallow cross rather than a vertical stem.
There are two slot receivers on this play, and, accordingly, two slot corners, but it is more difficult to gauge the play by the turn of the slot corners. Since there is no sideline, the receiver has a “two-way go” – he can release to either side of the defender. A slot cornerback in man-to-man coverage will turn to face the receiver regardless of whether that puts him facing the quarterback or not. If a slot cornerback executes a zone turn to face the quarterback even with his man releasing to the outside, that’s a good clue that he is playing zone.
Step 3 – Look at the Response to Motion
Often offenses will put a receiver in motion, running parallel to the line of scrimmage before the snap. This makes it hard for the defense to get a bead on the receiver and jam him at the line of scrimmage, and it also can force the defense to tip its hand pre-snap with respect to whether the coverage is man-to-man or zone:
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The Tennessee Titans send wide receiver Harry Douglas (#83) in “in-and-out” motion on the right. The response from the defense ‒ the cornerback trailing Douglas on his motion ‒ indicates man coverage in the secondary. The offense runs a switch vertical concept, with Kendall Wright (#13) – the middle receiver in the trips – running a post while Douglas cuts outside on a vertical route.
If the defender follows the motion man, that’s a pretty good indicator that the defense is in man-to-man. If the defense doesn’t react, or if it makes a different adjustment – perhaps the safeties or linebackers shift position slightly – that suggests zone:
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Clemson sends a man in motion before the snap, but Wake Forest does not send a defender to follow him, suggesting zone coverage. The Demon Deacons do use zone coverage here: Cover 3.
Step 4 – Look at the Linebackers (but not too closely)
The above three steps have focused entirely on the defensive backfield, with little information on the linebackers. There’s a reason for that: You cannot key off the linebackers as consistently. Rather, linebackers are often assigned a short zone even in man-to-man defenses:
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The St. Louis Rams are in a Cover 1. Linebacker James Laurinaitis (#55) shows blitz pre-snap, but drops into a hook / curl zone underneath. Linebacker / safety hybrid Mark Barron (#26) is responsible for Green Bay Packers running back Eddie Lacy (#27), but he also drops into a zone initially, only picking up Lacy after he crosses the line of scrimmage.
A Cover 1 defense generally has four pass rushers, five man-to-man defenders, and one deep free safety. That leaves an extra man, who can blitz, double a dangerous receiver, or read and react. One of the most common man-to-man defenses is Cover 1 Robber, where the extra man lurks in an underneath zone where he can react to the play without man-to-man responsibilities. Since linebackers often are better run defenders and worse man coverage players than defensive backs, it makes sense to use a linebacker as the robber.
Moreover, offenses do not always send all five eligible receivers into a pattern. Sometimes they will keep a tight end or a running back into block, and those are the players most likely to draw a linebacker in coverage. So you might see two linebackers in shallow zones, but it still doesn’t indicate a zone coverage, particularly if only four receivers are out in patterns.
The Montana play is an example of this: Two linebackers and the strong safety drop into underneath zones, but that still doesn’t rule out Cover 1. In this case, there is not only the typical extra man in Cover 1, but the RB breaks into his pattern late and there’s an extra pass defender because the line only rushes three:
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The two inside linebackers and strong safety all appear to drop into zones (purple circles), but that still leaves four defenders for the four receivers (yellow lines), so this could still fundamentally be a man-to-man defense.
Because linebackers are likely to play zone coverage, even in man-to-man looks, a linebacker playing man coverage is a pretty good indicator of a man-to-man defense:
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On this play, the Patriots split Rob Gronkowski (#87) out wide right, where outside linebacker K.J. Wright (#50) lines up on him. Seattle normally plays cornerback Richard Sherman on the right side (the defense’s left side), but Sherman has followed his receiver to the slot left, leaving Wright to take on Gronk. Quarterback Tom Brady (#12) reads man-to-man defense and attacks the matchup, throwing a touchdown pass to his big tight end.
Step 5 – Understand the Zones
One of the complicating factors in assessing whether a coverage scheme is zone or man-to-man is the principle of “pattern match” zone. Traditionally, defenders in a zone coverage backpedal to particular point or landmark. Those “spot drop” zones have fallen out of favor – unless you have a linebacker tandem like Luke Kuechly and Thomas Davis in Carolina, the holes in the zones are too large for modern passing attacks. One solution is the “pattern match” zone, where a defender is responsible for an area but actively covers his man within that area. Effectively run, a pattern match zone is the best of both worlds, combining the tight coverage of a man-to-man defense with the solid principles of a zone.
Pattern match principles make diagnosing defenses problematic. How can you tell the difference between a pattern match zone and a man-to-man defense? The key is knowing the basic rules for when a defender covers a man in his zone – and, tellingly, when he doesn’t.
First, it helps to familiarize yourself with the basic zone defenses if you aren’t familiar with them already: Cover 2, Cover 3, and Cover 4. Once you have a sense of the assignments for the defenders, you can start looking for patterns that do and don’t match those coverages.
Cover 2 – In a traditional Cover 2, the outside cornerbacks cover underneath zones on the outside. So in a two deep safety defense, watch how the outside corner reacts to vertical routes. Does he follow the receiver, or does he leave him to the deep safety? Shallow crosses are a similar story, as he will pass those to the adjacent linebacker or safety in Cover 2. If the cornerback is sticking with those routes, that suggests a man-to-man defensive scheme.
Cover 3 – The outside corners in Cover 3 are responsible for the deep thirds along their respective sidelines. On vertical routes, Cover 3 basically looks like a man-to-man defense. The best tell is the shallow cross – if he passes that off, it is a zone; if he sticks with it, it is man. This is key on the Montana play; the corner on the field side follows the shallow cross rather than passing it off. That’s a massive departure from the deep outside zone Cover 3 generally asks cornerbacks to cover. In Cover 3, we would expect that corner to be in position to defend the corner route from the slot receiver.
Cover 4 – A safety in Cover 4 is responsible for vertical routes by the slot receiver; if he sticks with the slot even if the outside receiver runs in a post or dig route, that is a hint it might be Cover 4. Like Cover 2 and Cover 3, the cornerback’s behavior on the shallow cross is another tip.
Even if you have only a rudimentary knowledge of the specific defenses, some of diagnosing zone versus man is common sense. If a defender starts out lined up in the left flat and winds up in the deep middle of the field, that’s man-to-man; no defensive coordinator would design a zone responsibility that expansive. If the receiver opposite a defender stays roughly where he starts, it’s going to be hard to tell man versus zone; you want to watch a receiver who moves from one part of the field to another and see if if the man opposite him early in the play continues to follow or passes the receiver off.
Step 6 – Break It Down If You Need To
You may get to this point and still not know for sure. Sometimes there are contradictions within a play as part of a hybrid scheme, a disguise, or a player missing his assignment – even NFL head coaches will tell you that you can not always tell if something was by design or just a blown assignment. At this point, you can make a chart of the options, breakdown the individual elements of the play, and note what fits and what does not. Here is such a chart for the Montana play:
The coverage is best determined not by the preponderance of the evidence but by the elements that are inviolable. It is possible to explain the press coverage the boundary corner plays if this play is Cover 3, or the underneath zones the middle defenders play if this is Cover 1. It is more problematic to explain the field corner following the crossing route in Cover 3, which is why I ultimately determined that this play is Cover 1.
Step 7 – Stay Humble
None of this is gospel. I’ve been wrong before and I’ll be wrong again. Asymmetric variants like quarter quarter half (sometimes called Cover 6) or “Cover 7,” and hybrid responses to stacks (like banjo coverage) or trips formations provide a nearly unending pool of information to consider when watching coverage.
Perhaps the most difficult call is evaluating what the coverage is when a player makes a mistake. The breakdown in Green Bay’s coverage in their overtime playoff game against Arizona is one example. Some players appeared to be in man-to-man and some in zone. I saw rookie cornerback Damarious Randall pass his man off to the middle of the field and assumed zone coverage, but according to Packers defensive coordinator Dom Capers, Randall should have stuck with his man when he crossed behind the underneath defender. Without knowing the playcall, it was almost impossible to know if Randall made a mistake or if it was another player.
One play during the 2016 NCAA National Title Game between Alabama and Clemson hammered home the difficulty of diagnosing defenses. Twice, Alabama overloaded one side of the field with vertical routes and scored long touchdowns. The all-star room of coaches on ESPN’s Megacast watched the second play multiple times… and still couldn’t figure out what the Tigers were trying to do:
Someone screwed up, of course – no coach designs a defense with a weakness that massive – but that brilliant collection of football minds couldn’t tell who was the culprit or what the coverage was supposed to be. Diagnosing pass defenses is a tricky business, and one that should be entered into with a heavy dollop of humility.
Step 8 – Forgive the Quarterbacks
If you have read this far, you should have a healthy appreciation for the challenges in identifying coverages. Even after studying pass defenses, making charts, and rewinding a play several times to check what each individual player is doing, you still may not know for certain.
Now consider: The quarterback has to do all of this in real time. He must identify the coverage, what adjustments his receivers will make based on the coverage, who is likely to be open based on the coverage and individual matchups, go through his progression reads accordingly, and throw the football to his receiver – all while navigating a collapsing pocket of 300-pound men bent on his destruction.
So the next time you lament Tony Romo throwing an interception or Andy Dalton missing a read or Jay Cutler being overpaid, consider the kind of mental processing they have to do in seconds or fractions of seconds, play after play, game after game, and cut them a little slack. Identifying pass defenses is not easy.
Thanks to Mark Schofield for providing many of the examples used here.