Fat Camp: Intricacies of cornerback play

It’s become common in recent times to say that the quarterback, left tackle and rush linebacker are the three most important parts when constructing a team, but that hasn’t always been the case. When John Madden used to talk about team building, he was very firm that the two most important things were your offensive line (especially the left tackle, but you need the whole group to be anywhere from solid to exceptional) and the cornerback slot. There’s good reason to still see things that way.  How important is the defensive secondary? Just consider these numbers:

  • 1977 - NFL teams ran 14,650 times (57.7%) and passed/were sacked 10,741 times (42.3%)
  • 1978 - NFL teams ran 16,075 times and passed/were sacked 12,850 times (55.6% vs. 44.4%)
  • 2010 - NFL teams ran 13,920 times and passed/were sacked 18,399 times (43.1% vs. 56.9%)

You easily get the idea: it’s not news that the NFL’s passing game has been bolstered since the (in)famous 1978 rule change that permitted offensive linemen to hold, as long as it was within certain parameters. That rule change began a long series of decisions that put the power in the hands of the offenses in order to make games more exciting to the fans.

Bill Belichick put it this way:

When you talk about the defensive secondary, you’re looking at one of the keys to the successful modern team. While the run - and the run defense - get more press at times, pass defense wins championships, game by game. The trick with them is threefold - you have to pressure the QB (and still stop the run), and you have to cover the receivers to prevent the QB from having options. That’s it in a nutshell.

For the 2011 Broncos, this threefold trick is being handled by these approaches:

  1. Moving to a new defensive front to stop the run and maximize pressure on the QB
  2. Adding additional players to upgrade talent, hopefully along the line
  3. Potentially changing the way that they use the cornerback position

The defensive front is something that I’ve covered as well as I can prior to the draft and free agency (see Fat Camp: Defensive fronts, Part I and Fat Camp: Defensive fronts, Part II): options for adding new players is something I’ve also noted at each front position (see Scouting the Broncos: Draft options and Denver’s #2 pick dilemma - prime or choice?). The changes to the defensive scheme will be interesting, with new head coach John Fox coming from a zone approach to the CB position and defensive coordinator Dennis Allen coming from the man-coverage, blitz-heavy approach of the Saints and Gregg Williams. Either way, Denver probably has the players that it needs at CB. I’m not suggesting that they can’t or won’t upgrade the position this year - that might happen, and I’d be happy to see more talent. However - Denver also has several good, young players in Perrish Cox, Syd’Quan Thompson and Cassius Vaughn who will need playing time to develop. Champ Bailey is locked in for four more years, which really helps if Denver decides to go with more man coverage. Cox did well for much of the year and showed the necessary mental attitude to play the position - cornerbacks have to get used to the fact that they’re going to get beaten and exposed at times.

This is how Bill Walsh put it:

...the cornerback must be emotionally resilient. He must continue to function after passes have been thrown in his vicinity, or after he has given up a touchdown pass. It takes a totally composed athlete to put aside these types of plays that will be obvious for everybody to see and judge. So they must have an inner confidence, to the point of cockiness, that demonstrates itself.

This is one of the things that you have to look at in evaluating the cornerback position. The player may seem excessively cocky in interviews, and you can’t let that go to the point where you’ve got personality problems on the team, or off-field incidents to deal with (which is what some teams are concerned with regarding Jimmy Smith, and the Broncos are currently experiencing with Cox). But at the same time, this kind of player needs that extra confidence, that ability to ignore mistakes while still learning from them and to come back on the next play with equal or more determination, focus and poise.

Via some help from my good friend Kirk Davis, I found a playbook of Belichick’s from 1997. It showed that in the coach's mind, the cornerbacks are usually responsible for the areas of the flat  - which is the area near the line of scrimmage next to the sideline and extending 10 yards from the LOS and the out, from 10-20 yards from the LOS and also at the sideline. Those two might also be covered by linebackers, depending on the scheme. By the way, Alabama coach and former Belichick assistant Nick Saban calls the area at 14-18 yards from  the LOS the move area, because that’s where the receiver is going to break in or out. The next area of responsibility is at the area from 20-30 yards from the LOS and again, starting at the sideline, which Belichick simply called the corner. After the 30-yard mark, the area next to the sideline is the deep outside, the next inward deep alley, which is the area from the numbers to the hashmarks, and finally the deep middle. Safety help generally comes in any of the deeper areas. It’s important to remember that safeties are usually tasked with responsibility for an area, not a specific player. However, in the pass-happy modern NFL, smaller safeties with better coverage skills are becoming the norm.

Press, bump or bump-and-run coverage

These are various ways of saying much the same thing, and it’s essential in NFL football. It’s a basic pass coverage technique in which the defender aligns on the inside shoulder of the receiver and immediately strikes him (inside hand on outside release, outside hand on inside release) when he first moves. It’s designed to prevent or delay the release of the receiver on a pass route. The CB on press-man coverage needs to be able to mirror well to maintain coverage. College CBs don’t usually have to cover using press that often, but it’s a constant requirement for the outside CBs in the pros.

Tight and off coverage

These are pretty self-explanatory. Off coverage can give up the short pass to the flat, but gives the CB a better chance in covering a ‘go’ route - one in which the receiver tries to fly down the line at top speed.

You will often hear fans complaining when a CB is in off coverage and a completion takes place in front of him, leaving him to make the tackle and give up the yards, especially if the CB is in over coverage (see below). It’s not his fault - that’s the nature of the coverage. You’re willing to give up short passes to force a lot of plays on a drive, increasing the chances that the offense will make a mistake. If you’re blaming someone for the CB playing off, blame the coach or the system. The CB is just doing his job.

Tight coverage requires excellent skills at mirroring the receiver, and the CB has to be aware of where the ball is. A moment’s hesitation in finding the ball can lead to a reception.

Many Denver fans remember the frustration with former Bronco Dre' Bly playing opposite Champ Bailey. Bly was a better CB than he showed in Denver, but not all of that was his fault. Bailey’s preference is to start in off-coverage with his back to the sideline to see the QB and his assigned receiver. Bly was best in press coverage, but was required to ‘mirror’ Bailey’s approach. It’s a good lesson for the upcoming season, whenever it comes along - make sure that you have CBs that fit exactly what you’re going to ask them to do.

Basic route coverage

Receiving routes generally follow a specific pattern, and it’s tied to the number of steps that the QB drops. Receivers generally make certain moves at certain points from the line of scrimmage. To successfully cover them, the cornerback has to have a wide swath of skills.

Making the reads

Before the cornerback begins his backpedal, which is an art in itself, he must make two key reads. First, he has to see if the QB is going to throw the 'smoke' route, in which the passer simply straightens up and throws to a predetermined receiver. That's a tough pass to stop unless the defender spots a 'tell' of any number of types. The WR may stand a little differently, the QB might stamp his foot differently or shift his weight a little; the other WRs might stand differently since they are going to block; the same goes for the OL and the TE(s). With that one settled, the defender has to watch for the 3-step drop routes. Those routes are the hitch, the out, the slant and, of course, the smoke (which can be thrown immediately when a QB sees the corner playing off).

If those are not involved, then the cornerback has to go into his backpedal, realizing that if the route doesn't break at the 5-7 yard points (as all 3-step drop routes do), then it's going to either be a 9 route (streaking toward the endzone) or break between 12-15 yards from the LOS. His hips must be low, to permit him to move his weight and to cut more effectively. His steps must be small and smooth for the same reason. It's a tough skill to master, no question. Other than the routes covered, you only have the 9 route, often called the 'go' route and the fade route which corners can diagnose by the receiver running at top speed and not breaking down in the 12-15 yard area. Of course, a canny receiver can also run a double hitch or stop-and-go route - there are infinite ways to vary the routes to confound the defenders.

"You have to limit those big plays," Champ Bailey once said. "And (against) offenses that throw it quick, anticipation is the difference. If you can study and anticipate, you can always play faster than you are." Needless to say, a lot of the cornerbacks’ responsibilities start in the film room. they have to study their opponents' tendencies, as individual players and as teams. It’s a lot to learn, and having Champ in the film room with them is an open invitation to a seminar on the game, week after week. It should help the younger players develop.


There are four different WR screen plays – bubble, tunnel, slip, & crackback screens. If you want you can throw a smoke route in the mix though it isn’t technically a screen play. Every screen is not a bubble screen, although you’d think so from listening to certain announcers.

Underneath and over the top

These are just options for covering a receiver. Underneath is covering closer to the LOS - the CB can try to ‘jump the route’ for an interception, and usually the CB will have safety help over the top in such cases. If the CB (or safety) is covering ‘over’, or over the top, he’s between the receiver and the goal line. If the CB is in coverage underneath, he almost always has or expects safety help over the top. However,  unlike the CB the safety is tasked with an area of responsibility, not a specific player.

Cloud and sky coverage

I’ve heard these terms defined in two slightly different ways, so I’ll mention both: one emphasizes the area of the flat, while the other deals with the back end of the field. In both, the terms ‘cloud’ and ‘sky’ are used in (mostly) zone coverage situations to designate whether the cornerback or the (usually strong) safety has certain responsibilities. It works like this:

Cloud coverage is a zone pass coverage in which cornerbacks cover passes to the flat; both cornerback and cloud start with the letter C

Sky coverage is a zone pass coverage in which safeties cover passes to the flat; both safety and sky start with the letter S; opposite of cloud coverage which has the corner cover the flat.

In Cloud coverage, for example, in a Cover-3 situation where the deep field is divided into thirds, one CB on one side stays underneath, protecting the flat. Meanwhile the safeties roll to that side with each taking one third of the deep coverage responsibilities and the opposite CB retreats to a deep-third or -quarter coverage to protect his area.

But there’s a different way to discuss the term. I find this one more common - Footballdrills.com put it this way:

The distribution of the deep zones gives the defense again two alternatives: Normally the Free Safety will cover the deep middle and one Cornerback one deep third on his side - and the Outside Linebacker is normally responsible for the "Flat", that is the short outside zone. On the side of the Strong Safety there are two options: The Strong Safety takes the deep third or the Cornerback takes the deep third. The corresponding other is responsible for the flat. Often you hear something like "Cover 3 Sky" or "Cover 3 Cloud": Sky = Safety covers deep, Cloud = Cornerback covers deep.

Run responsibilities

Stopping the pass, while the primary role of the CB, is only one of the requirements of the position. If a team doesn't have to pass on you to beat you, they'll run at you and run out the clock. A cornerback who has good recognition on run/pass as the play begins can move up to help out against the run. Every coach hopes for a CB who has fluid hips, runs like a deer and covers like Velcro®, but they are also looking for a CB who doesn't mind getting his uniform dirty and tackles like a linebacker. Champ Bailey is one of those, and they make the job of stopping the run and the pass a lot easier.

Once  you’ve stopped the run, your secondary should work concurrently with the rush to keep the passing game from tearing you apart. Pressure on the QB and/or the RB in the run game by the line and linebackers is essential - given enough time, every NFL team can get players open. But once that pressure is on, your DBs have to keep the receivers from coming open while the pass rush does it’s thing. The longer they can cover, the better the chances of a sack, incompletion or even a turnover.

Stray Notes:

  • You almost never have to beat press coverage against Cover-1 or Cover-3. On the other hand, you will almost always have to beat a press against Cover-2, whether zone or man.
  • On timing routes, which are one of the basic building blocks of the West Coast Offense, applying press.bump coverage can throw off the timing enough to defeat the play. Announcers and many fans will often say that the QB missed the throw on those, but it was often the CB’s play on the WR that created the incompletion. You can’t tell by looking - you have to know the play call. That’s common to a lot of situations while watching games.
  • If you’re trying to beat a Tampa-2 defense, the receiver has to run his ‘divide route' (just what it sounds like) correctly. The seam is one of the biggest areas of weakness in the Tampa 2, since properly run, it splits the defenders’ responsibilities, creating an opening.
  • Press coverage is far more common in the NFL than in the college game. If you want to run a streak choice to beat a corner in press coverage, the comeback has to happen between 12-15 yards because that’s where the QB will throw it. Again, this is what Saban calls the ‘move’ area.
  • If the coverage is sky strong, the X receiver has to run a crisp slant route. Running that slant will get the receiver open, regardless of the system. To counter that, the defender has to hit the receiver in press to slow him enough to throw off his route or shadow him well enough to deflect the pass - preferably both.


It’s probably obvious, but covering the full subject of playing cornerback is as much suited to a full book as an article. Even so, I hope that this has provided some information that may help some fans appreciate and understand the game a little better. The next installment will break down Denver’s CB situation and suggest where the team might go next.

Go Broncos!

Learn to laugh at yourself. You will be ceaselessly amused. - Sri Gary Olsen

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