Cover 3 is a weekly feature column written by’s Tampa Bay Buccaneers beat writer Trevor Sikkema published every Tuesday. The column, as its name suggests, comes in three phases: a statistical observation, an in-depth film breakdown, and a “this or that” segment where the writer asks the reader to chose between two options.

… But you can throw all that out the window this week, as I’ll be dedicating each page of this Cover 3 to explain, in depth, the different kinds of assignments, roles and responsibilities that go into each defensive coverage design in the game of football.

Sikkema’s *Scheme of the Week Part I

In last week’s Cover 3, we went over why size matters, and how the moves and priorities the Tampa Bay Buccaneers made this offseason, both in the draft and in free agency, showed a team-building philosophy worth supporting.

To conclude that article, I opened up future Cover 3 topics to you all, at least in the short-term, before training camp starts. I gave you all – the readers – the chance to fire off some ideas about the game of football or the Buccaneers specifically that you would like to see me dive deeper with. There were a few answers that I really liked, and after going back and forth in my head about which one I should choose, I realized that I could do almost all of them in a sequence that could make sense.

This week we’re going to talk about defensive coverages. I’m going to breakdown the terms, assignments, roles, along with the strengths and weakness of each and why they all exist when defending the pass and simultaneously helping the run. Next week I’m going to build off that and go into a film review of quarterback, Jameis Winston. We’re going to take the knowledge we’ll gain from this week’s Cover 3 and lay it over Winston’s pre-snap reads; how he’s seeing the defense before the play begins and if he’s recognizing or attacking things correctly. Finally, the following week, we’ll examine his deep ball. I’ll try and find every pass of 30 or more yards that Winston threw from the 2016 season, complete or incomplete, and analyze just *how* he needs to improve with those passes, not just saying, “Well, he has to be better” without context.

If we have some extra time before camp, I might get into some in-depth offensive line previews as well as some previews of the Buccaneers’ NFC South opponents, but part of me wants to save those for closer to when the season starts.

So, that’s the plan right now. Let’s dig in with some defensive coverage terminology.


In order to understand a lot of what I’ll be explaining on the next few pages, I first want to make sure we define some terms I’ll be using – there’s nothing worse than reading a really good football breakdown and all of a sudden being thrown off by a word or term that gets continually used but never explained or explained simply enough.

Outside Corner Concepts

New York Jets CB Darrelle Revis (Photo by Jim McIsaac/Getty Images)

“Star” Concept: The “star” concept is just straight up backyard football. It’s the best players going up against the best players. A defense will take its best cornerback and assign him to the offense’s best wide receiver. That cornerback will follow that receiver wherever he goes on the field. Left, right, inside, outside, it doesn’t matter. That’s why it’s called the “star”; your star versus theirs. The other cornerback(s) will have their assignment(s) after that to match talent levels.

There aren’t many cornerback who do this anymore. Deion Sanders made it famous back in his day, and Darrelle Revis when he was with the Jets was probably the last to do it consistently.

Split Concept: The split concept is where the two outside cornerbacks will each play one side of the field exclusively and not flip sides, even if there is a mismatch on one side or the other. This is a difficult concept to rely on heavily because there is a greater potential for a mismatch, and you never want to put yourself in a hole before the play even starts. However, if you have two cornerbacks who are good and can take on all kinds of receivers, it is advantageous because it never gives away what look the defense is presenting because there’s no movement to players in motion. It requires more, talent wise, but can be deceiving for an opposing quarterback. This is your Richard Sherman, Seattle Seahawks type of concept, but it has since been adopted by most of the NFL – just deployed in different coverage shells.

Boundary/Field Concept: The boundary/field concept is one that is emphasized much more at the college level because the hashmarks are much further apart in the NCAA than in the NFL. This concept once again focuses on the two outside cornerbacks. The boundary cornerback is the one that is lined up on the side of the field that has less space. On the flip side, the field corner is opposite them with more of the field to cover – boundary is closer to the boundary, field covers more of the field.

Boundary corners are generally the more talented cornerbacks because, with less space needed to cover, they get less help from the safety. Boundary corners have to be your “island” corners who can succeed without help. Field cornerbacks have to be athletic to cover ground, but they know they have help behind them. Boundary corners do not. The knowledge of this concept is used more for scouting than deployment at the NFL level because with the hashmarks closer together in the NFL, the space required to cover for each cornerback is relatively equal.

The “Other” Guys

Denver Broncos CB Chris Harris

Denver Broncos CB Chris Harris/Getty Images

Nickel (Sub) Corner: The nickel cornerback is also called the “sub” corner because they are the one who comes in on “sub” packages when the defense goes out of its base 4-3 or 3-4 to help defend the pass. Nickel corners have different roles depending on which coverage shell is being deployed, but, for the most part, just know that they’re the cornerback that lines up against slot, or inside, receivers. That could be a wide receiver or a tight end. They’re also generally in man-to-man coverage. This means that slot corners are no slouches. They’re not just the third best cornerback on the team anymore. Teams have used players like Chris Harris, Kareem Jackson and Micah Hyde strictly in slot roles, knowing they could play outside corner. It’s like strategically having a probable starting player as your sixth man in basketball.

Free Safety: Most of you know what a free safety is already, but I want to make sure I’m covering my bases on everything because safety play and the two different roles are important for every kind of coverage shell. Free safety is the safety that is playing as the “last resort” player. It’s this player’s job to make sure that nothing gets behind them. Free safeties are often asked to cover very large areas of the field, and must be athletic enough to do so. They are for the more speedy, coverage kind of safeties. The best examples of a free safety in today’s NFL are Earl Thomas and Harrison Smith. Sometimes you’ll see cornerbacks get converted to safety in the NFL, and when that happens, they generally go to free safety because the skills are similar, like Tyrann Mathieu – though he play strong safety, too, he’s just really good.

Strong Safety: Strong safeties are your run supporting defensive backs. With each coverage shell we’re going to go over, if you read that only one of the safeties is back in coverage, it’s because the other is either helping in the run with the linebackers, or is covering a passing assignment closer to the line of scrimmage. These assignments are for the strong safety – they also generally line up on the “strong” side of the field where the tight end is in case it is a passing play and they have to cover the tight end. Strong safeties certainly have to have coverage abilities, but they also have to be linebacker-like (or lite) as tacklers with strength and size. For examples of top strong safeties, look no further than Kam Chancellor, Eric Berry and Reshad Jones.

Defensive Back Alignments

Off Man: There are two types of alignments defensive backs can have when lining up against receivers near the line of scrimmage. The first is “off man.” Off man is another way to say off coverage. In this alignment, the defensive back usually gives around six to eight yards of cushion between them and their receiver before the snap. The purpose of this is the keep everything in front of them. If the receiver does any sort of slant, curl or out route before five yards, the cornerback would hopefully be able to read the quarterback’s eyes and either take away the pass, break the pass up or get there quickly for a tackle. This kind of coverage also helps defend deep passes, as the wide receiver likely won’t be even with a defender running down the sideline until about 15 yards down the field.

Bucs CB Brent Grimes – Photo by: Cliff Welch/PR

It’s a damage control kind of alignment. It gives up yards, but, in theory, no big plays. One of the best cornerbacks in the NFL at playing off coverage plays right here in Tampa Bay in Brent Grimes. Most of Grimes’ interceptions this past season were anticipation plays, and he was the best defender in the league against the double move. He keeps things in front of him, he doesn’t get beat deep, and he can make a break on a ball in the blink of an eye.

Press: Press coverage is the higher risk, but also higher reward of the two styles of defensive back alignments. In it, the defensive back lines up right in front of the receiver they are defending. Press coverage usually comes with a press at the line of scrimmage (hence the name). A press is when the cornerback immediately gets his hands up and into the chest of the receiver right at the snap (which is allowed in the first five yards from the line of scrimmage) as to either delay, lock up or re-route a receiver off the start of his route.

As you can imagine, a successful press can do a few things. It can mess up the timing with the quarterback and the wide receiver, it can potentially shut down any short routes, and it allows more time for the pass rush to collapse the pocket. With the cornerback so close to the wide receiver at all times, the chance for turnovers increases. However, with no cushion for coverage, and the safety likely deeper in the zone, there is a vulnerable spot about five to 15 yards down the field along the sideline where the receiver can be open if he breaks the press well.

The best at press coverage are some of the most notable names in the business. These are your Richard Shermans, you Janoris Jenkins’ and your Jalen Ramseys. These are also the players that would be your No 1. if you were playing a “star” concept.

Fraction Coverages

Halves Coverage: The next three coverage terms are pretty simple to understand because their names say it all. All of these three terms will be talked about regarding the deep coverage zones. In halves coverage, the deep part of the field is cut in half. One side is taken by the free safety and one side is taken by the strong safety. This is the kind of deep coverage that is used for Cover 2 where the cornerbacks are in man coverage or close coverage, but the safeties are still both playing deep.

Jalen Ramsey Jaguars

Jacksonville Jaguars safety Jalen Ramsey

Thirds Coverage: The next coverage fraction is thirds. This is where the deep part of the field is cut into three segments. The middle of the field is covered by the free safety while the strong safety is free to roam near the line of scrimmage or help in run support. That leaves the two outside cornerbacks to man the outside deep zones. This is what you see what you hear a defense is running “Cover 3.”

Quarters Coverage: The final type of fraction coverage is quarters. This is when both the free safety and strong safety are covering deep, but, unlike the halves and Cover 2 concept, this type of coverage also has the two outside cornerbacks drop deep as well. This is the kind of coverage you see in prevent defenses; four players covering four deep zones with a lot of help to one another. This is great for defending Hail Mary passes. However, if you ask me, teams use quarters coverage way too much late in games and actually just end up putting themselves in bad situations giving up tons of yards.

Variants of Fraction Coverage

Sky: Each of the three terms we’re about to discuss have to do with playing a three-deep zone – or thirds or cover 3. In “sky” coverage, we see the traditional two corners and a safety occupy the three deep zones. Sky is just another way of saying the field is divided into thirds, but specifies that it is, in fact, the two outside players and free safety who take the back end.

Cloud: “Cloud” coverage is a different variant of the “thirds” fraction coverage. Instead of the strong safety being the one who is free to roam near the line of scrimmage, both safeties and one cornerback occupy the deep zones in cloud coverage, which leaves the other cornerback to either occupy a shallow zone at the line of scrimmage, or possibly blitz off the edge. This could be confusing for a quarterback who might look one way and see a defensive back dropping deep, then look the other and see the cornerback in a shallow zone. If the quarterback is confused at all, a likely sack is about to happen. Cloud coverage is often deployed in Cover 6 shells, as we’ll explain later.

Rolling: “Rolling coverage” is when the defense shifts after the snap to provide extra help on one side of the field. In a cloud coverage scheme, the defense will often roll in the direction of the one cornerback who is not covering a deep zone. One safety would shifts to a position behind that cornerback, the other safety would move to the middle of the field, and the other cornerback would drop back as normal. Plus, a linebacker would likely slide into the flat in front of the one corner covering deep. It’s hard to tell who is responsible for which zone with all that movement, and places a quarterback thought he might have as a hole in the zone are no longer there.

Protecting the Seams

“Hole” (Seam): The hole or seam in a defense is what every player, on both sides of the ball, is thinking about at all times. There are three main seams or holes that an offense can attack. Two are along the sidelines at about 5 to 15 yards down the field, and the other is right behind the linebackers and before the safeties in the middle of the field.

Defenses can’t cover everything; they just can’t. But, they can fool an offense into thinking they’ve covered everything. That’s the purpose of different types of coverage shells. Each is designed to get the most out of the skill sets you have on your roster by making a quarterback think that there’s no where to go when, in realty, there almost always is.

With these terms and definitions in mind, let’s go over the many types of coverage shells there are, which ones the Bucs run, and why run them.

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About the Author: Trevor Sikkema

Trevor Sikkema is the Tampa Bay Buccaneers beat reporter and NFL Draft analyst for Sikkema, an alumnus of the University of Florida, has covered both college and professional football for much of his career. As a native of the Sunshine State, when he's not buried in social media, Sikkema can be found out and active, attempting to be the best athlete he never was. Sikkema can be reached at:
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4 years ago


Thanks for the clear presentation.

4 years ago


This is great. I thought it was really helpful. I think that it may have been interesting going into a little bit of detail about what went wrong on defense last year against the Raiders and Falcons when the Bucs gave up over a thousand yards in a couple weeks.

I know that would have added a lot to your word count though. lol.

4 years ago

I feel like the student just begining a course who tried to speed read the entire textbook in an effort to understand the challenge ahead!

This will take some time and study, and working some sample problems before it will all sink in (speaking as a graduate engineer who had to work hard to get thru the curriculum). But Trevor, if you keep referencing these concepts as we progress through the upcoming season (as you say you will do) the payoff will come in much better understanding of the game.

This is a great feature, and only available on PR.

4 years ago

Enjoyed it. One clarification (or thing to add). Most teams run “read” “match” or “liz/rip” coverage concepts where the players read patterns on-the-fly which changes their coverages.

Almost all Cover 4 is actually “cover 4 read” wherein the corners aren’t actually dedicated deep quarters but are reading routes and often play low depending on routes/formation. Thus you can turn Cover 4 into Cover 2 purely based on offensive routes (which is also why its harder to read coverages now).

A good example, with some fun variations, is Pat Narduzzi at Michigan St:

Reply to  Trevor Sikkema
4 years ago

Narduzzi’s C4 is definitely different than how most NFL teams run it, much more aggresive/press. Some good stuff on Saban’s rip/liz (form of read): Chris Brown has a couple of really fun articles that discuss it in relation to TCU and Michigan: There are definitely more technical articles/videos (I can always send you some) but these are great jumping off points (and well written). Up here in Canada we’ve been playing “read” or “pattern matching” for 10-15+ years. My understanding is that Saban popularised it down in D1 college (could be wrong). It’s a ton of fun… Read more »

Reply to  tog
4 years ago

It does fit the Bucs corners though. I felt like (you’d know better) that Smith ran more C4 (read) last year than any other coverage. But again, with the read/pattern-matching it can be near impossible to tell apart from C2/C3.

4 years ago

My mind is completely blown.

4 years ago

Another excellent and engaging piece man. Learn something new everytime. And I agree full heartedly with your comment about Quarters coverage, I honestly want to know why it is deployed by defenses other than a hail mairy pass play… Furthermore if this were a parallel universe and I were ever a GM of an NFL team lookong to hire a new coach…it would be an interview question of mine…”How do you feel about using “Quarters coverages” during 4min 2min, 2possession 1 possession games?” And I would seriously weigh my decision on their answer…(or even fire them after the fact). Because… Read more »

4 years ago

I mean, I’ve played a lot of Madden but… nice work man! Greatly appreciate the information!

4 years ago

A lot to take in but I really enjoyed it.

4 years ago

Great break down. It is revealing to see and understand just how important the role of QB now is in the game. And of course at field level, everything looks different. As a team you have to make a choice to simplify the decision making process or have a QB that is immensely talented in information processing. When you see the Tandy interception on Brees it struck me how this fooled Brees so much. It was a combination of a great timing play call for Smith, great read on Tandy but also a really poor decision by Brees.