The most common defensive scheme in today’s NFL, only five teams averaged a Cover 3 — also referred to as 3-Deep Invert or ”Sky” — rate less than 20% last season. The league average falls around 28%, but that number jumps to 35% for the franchises with the top half of the highest usage rates. One of the main factors drawing DCs toward the scheme is how easily it can be disguised as a pre-snap Cover 1. Since the primary focus of every defense is to stop the run, Cover 3 points the defense toward accomplishing that goal on three fronts. With the Cover 3 strong safety (SS) dropping down into the box, the defense is provided with the strength from one additional defender than the offense can block. The second benefit of the coverage is forcing opposing offenses to determine if they’re playing Cover 1 or Cover 3. Finally, on the plays where they are actually in a Cover 1, once again, they have the benefit of the SS in the box.
The most significant issue for Cover 1 is the complete vulnerability to the deep ball. The single-high safety is left to platoon all three deep zones by himself. But Cover 3 drops two additional defenders — both outside CBs inside the standard scheme — to defend each of those three deep zones. It comes at a price, as two underneath zones are left uncovered. It’s a weakness rendering the scheme vulnerable to a list of patterns with receivers who can “catch short, run long.” However, it’s a risk worth taking. The three most effective coverage schemes at stopping the run from last season were, in order: Cover 0, Cover 3, and Cover 1.
Another benefit of Cover 3 is, with perfect timing on the blitz from the free safety (FS), it can also be mistaken for Cover 0 — zero deep defenders, all-out blitz. In fact, the three teams utilizing the highest rates of Cover 0 last season (Dolphins, Patriots, and Ravens), also played Cover 1 at a top-10 rate, and Cover 3 between 28-30% of all snaps. It should come as absolutely no surprise that the five defenses who played Cover 3 the least last season (Chiefs, Jets, Titans, Raiders, and Saints) were completely picked apart when calling for an all-out, Cover 0 blitz. Each of those defenses allowed a bottom-10 ranked passer rating, with zero INTs to 23 combined TD passes allowed.
From a standalone perspective, what were the three least effective schemes in terms of passer rating allowed last season? In order: Cover 0, Cover 3, and Cover 1. The exact order from the list above of the best vs. the run. But some DCs have already caught on to that fact. To counteract offenses attacking Cover 3 through the air, we are seeing some slick defensive adjustments.
The Rams, Colts, Bears, and Chargers are at the forefront of fielding a scheme referred to as 3-Seam. The shell calls on matchup-zone principles that are precisely schemed to take away the kryptonite of Cover 3: receivers attacking vertically down the seams between each deep defender. Keep in mind that a Cover 3 is only provided with four defenders to guard the six underneath zones. In a 3-Seam, two of those underneath guys — the curl-flat defenders — will “spy” on the No. 2 receivers (slots), and defend them throughout on any out-breaking or vertical patterns.
While 3-Seam is growing in mainstream appeal, the other Cover 3 shift is still in its infancy. Brought about in college football’s Big 12 conference, teams installed the “Cloud” shell in order to defend the explosiveness of Air Raid offenses. With those Air Raid principles flooding into the NFL, it was only a matter of time for the Cover 3 variant to follow. The defining characteristic of the “Cloud” — also referred to as 3-Cloud — is confusing the offensive reads on which three defenders will drop deep. In a straight Cloud (rather than its sister scheme, 3-Double Cloud) one outside CB and both safeties drop back to defend the deep zones. The other outside CB is tasked with jamming/redirecting the No. 1 receiver to his side of the field. It’s an adjustment that prevented NFL offenses from finding the end zone on over 100 defensive snaps last season. The 3-Seam alternative limited offenses to a one-to-one ratio of TDs-to-INTs, and only trailed 2-Man for the lowest passer rating allowed last season.
Every defense must disguise their coverages, for obvious reasons. Every team must put examples on tape of fielding both man and zone principles, with one, two, three, or four deep defenders. The constant tug-of-war between offenses discovering new techniques of identification and attack, and defenses deriving new strategies to get home, can throw off the QBs timing and recognition of the offensive schemes. The very best DCs draw from any method available, at any level of play, and in a constant state of schematic evolution. In fact, some of the most popular offensive and defensive techniques have their origins from the high school game. Teams want to be the first to implement new-age nuances, never those that are forced to find ways to adjust.
Pre-Snap Reads by the QB to Identify Cover 3
Cover 3 is referred to as an “invert” due to the depth of the SS. When he has less depth than the strongside CB, his alignment is inverted. And that’s precisely what the QB uses him as his primary read to identify the scheme. When he sees that shallow SS, he “knows” that defender will be reading the flat. The QB must keep a watchful eye on the SS. And he must also be well aware of his level of athleticism. The Cover 3 SS is a primary threat for jumping down on routes. The QB uses the station of the FS to verify the three-deep shell. When the FS aligns in the very center of the field, rather than aligning on either hash, it’s a distinct tell. Even when defenses attempt to move their safeties around (i.e., Buzz) or delay their landmark timing, both safeties must be in position at the snap.
The QB must also identify the underneath defender to the weakside. Why? If he’s able to determine that a LB is responsible for the flat, he becomes the clear target of attack. The QB can spot that role for the Will linebacker if he is either stacked directly behind a D-lineman, or entirely outside of the tackle box. Several of the most successful methods to attack a Cover 3 at all three levels are directed at picking on a Will LB defending the weakside flat. The third, final pre-snap read from the QB is determining if either defensive end will drop back as the curl-flat defender. It’s all about the DEs stance. If he has his hand in the dirt or is simply up on the LoS, it is safe to assume he will rush the pocket. Those three reads should allow the QB to verify a three-deep shell to a high degree of certainty. Even the greatest QBs in the history of the game will get some of their reads wrong, but close to 75% accuracy is the goal.
Reads by the Cover 3 Cornerback
To be clear, we’re only looking at the role of the CBs dropping deep in a standard Cover 3. Inside those Cover 3 variants, CBs defending underneath zones present the QB with a different set of issues. In the Cover 1 piece, I mentioned that man and zone CBs utilize a vastly different pre-snap checklist. That’s only true in regards to the contrasting approach to the coverages. The differences are (intentionally) so sudden that they appear damn near identical. And that is the ultimate goal of disguising their defense. Man and zone CBs are tasked with remaining faithful to the exact same checklist, but must spot vastly different offensive attributes. But they are still watching the eyes of the QB and WR, reading the amount of time it takes the offense to get set, looking at the alignment of each eligible receiver, listening for certain words in the QBs cadence, and hoping that any of the indicators the team may have spotted on tape will show up on the field.
Since the Cover 3 CB is obviously aware of his coverage scheme, he already knows every one of the weaknesses presented by the defense. Even with that knowledge, he must adhere to the requirements of the coverage. In Cover 3, the CB will position himself differently based on the offensive formation. But both outside CBs will align no closer than seven yards from the line of scrimmage. The primary requirement for a CB with deep field responsibilities to “break character” is precise communication with his FS. Even if he is cleared by the FS to attack a route based upon his reads, leaving the FS to cover two-of-three deep zones by his lonesome is a dangerous proposition. That’s precisely why the QB is mostly concerned with the post-snap actions of the SS. He is the unknown wildcard who can blow up the play. That said, when the flow of the play is away, the CB does have the freedom to cheat toward the flow of the play; provided the CB maintains outside leverage on all receivers.
Strengths of Cover 3
Very strong vs. the run.
All three deep zones are covered.
Risk vs. the pass is minimal as long as tackling is sound on underneath receptions.
Capability of covering all eight zones when only rushing three.
Presents options for masking specific man coverages when used in conjunction with Cover 1 and/or Cover 0.
QBs must deal with the rovering SS wildcard.
Weaknesses of Cover 3
Any reinforcement adjustments into pass coverage limits the pass rush potential.
In the base package, two underneath zones are left uncovered.
The seams in between those four underneath defender’s zones are significant gaps of attack.
Risk vs. “Catch short, run long” is very high.
Vulnerable to attacks at specific levels of the scheme:
Curl/Stop routes between underneath defender zones
With only three deep defenders, sending four verticals can result in busts when read incorrectly.
How to Attack Cover 3 in Fantasy
As mentioned above, if we can identify the defenses that attempt to send all-out, Cover 0 blitzes without accompanying Cover 3 usage, we are in business. Coming into that information is obviously the issue. Nearly half (13) of the DCs from last season have been replaced. That’s a staggering number. It means we’ll need to wait at least three weeks into the season before any coverage patterns emerge for the teams with new DCs. But we will still have the other 19 defenses that pack along at least a full season of historical tendencies provided by their returning DCs.
Since attacking a Cover 3 over the top is so difficult, catch-and-run/after-the-catch receivers offer the highest upside. However, no team will ever play solely from a Cover 3. We need the full breakdown of the team’s defensive coverages to pinpoint our targets.
In general, we want to see an offense attack a Cover 3 both vertically and horizontally. When facing defenses that utilize the disguise-rich trio (Cover 3, Cover 1, and Cover 0), we want our QBs to have strong pass protection in order to counter the pass rush. Otherwise, those are clear QBs to avoid during that week. With the exception of teams that lack difference-making defenders, avoiding one-dimensional RBs in those matchups is also an intelligent move. When we know receivers are facing a 3-Seam heavy team, it’s usually the best idea to avoid the strictly-vertical variety, within reason. But we do want to have exposure to our PPR darlings. They may not reach paydirt, but the basis of the 3-Seam is to remove all deep seams, limit damage, and eliminate anything deep. Underneath targets are essentially funneled without much resistance. Of course, the individual history of success facing Cover 3 should always dictate our final approach.
2020 Defenses Utilizing the Highest Rate of Cover 3
Cornerback Shadows to Avoid
Off-the-Ball Linebacker Shadows to Avoid
- Darius Leonard
- Demario Davis
- Devin Bush
- Blake Martinez
- Matt Milano