In the first page of our article on defensive football plays and schemes, we covered defensive fronts, pass rushing and some of the more exotic blitz packages, such as the Zone Blitz and the 46 Defense. But this is only half of a pass play.
If getting to the passer is one way to stop passing offenses, then pass coverage is the other side of the coin. Defenders in pass coverage are those who choose not to rush the passer, but instead to defend against those players who might receive the ball from the quarterback.
To defend against a pass is termed "covering the receiver".
There are two different strategies in coverage. One, the pass defender can attempt to intercept the ball, causing a change of possession. Two, if the first cannot be achieved, then the player will attempt to deflect the ball, making certain the receiver does not himself catch the ball. This causes an incompletion, and the ball returns to the spot where it was last snapped with the loss of a down.
Sometimes, defenders cannot reach the ball, and therefore must distract the receiver or simply make the catch more difficult. This might be done from cutting off the passing angles, forcing the quarterback to make a perfect throw to the receiver, or preparing to hit the receiver as soon as the ball is caught, knocking the ball away.
Even if a hard hit cannot separate the ball from the receiver outright, hard hitting defenders can sometimes intimidate or distract an opponent from catching the ball, essentially breaking their concentration.
So far, the discussion has been about single coverage, but there are actually schemes which entire defensive units use to defend against the pass. The two major schemes are zone and man-to-man defense.
Man-to-man coverage is the simplest form of defense to picture. Each receiver is covered by a defender, who follows the receiver around the field and tries to defend the pass.
In the case of a wide receiver, a cornerback locks up in man-to-man coverage. In the case of a tight end, a safety usually covers the tight end (though linebackers sometimes do). In the case of running backs, linebackers often attempt coverage, though this can cause match-up problems for the defense.
If only one opponent covers a receiver at one time, this is called single coverage. Double coverage is also common.
Often, an offense has one or two players who are their most skilled or most dangerous receivers. These players will usually face double coverage, to try to eliminate that player’s effectiveness in the routes. If a player is skilled at running routes, a second defender is needed to keep the ball from ever reaching the receiver. If a player has great speed or cutting ability, two defenders might be employed to make sure the tackle is made after a catch.
In double coverage, there is usually underneath and deep coverage. Underneath coverage is usually done by a cornerback and linebacker, meant to stay between the receiver and the quarterback and cover any "short" patterns.
A safety usually completes the double-team by taking deep coverage or "over the top" coverage. This means the underneath defender can concentrate on defending the pass and looking for an interception, while the safety makes certain the receiver does not get behind the defense for a long pass. Also, if the ball is thrown underneath, the safety makes certain a tackle is made and might go for a big hit on the receiver.
If a defense rushes the passer with 4 down linemen, this means there might be two double coverage situations in coverage. The offense has 5 linemen who cannot act as receivers and 1 quarterback, so at least 6 players are not releasing into passing routes. This means there are 5 potential receivers against 7 defenders. Sometimes, a running back or h-back is kept in to block, if the defense’s pass rush is particularly stout or a blitz is expected.
Zone defense requires defenders to defend specific zones in the field instead of specific receivers. For instance, the two cornerbacks might cover their side of the field outside the hash marks, while a safety covers the deep middle of the field. Linebackers might cover underneath zones, while the strong safety might do the same.
The advantage of the zone defense is it allows defenders to work together, especially in situations where the defensive players have trouble keeping up with certain receivers on the other side of the ball. If the opponent has such a speed advantage that man-to-man coverage isn’t working, then a zone defense might give the defense a better chance.
The disadvantage of the zone defense is an offense with smart receivers and a smart quarterback can find the "seam" in the defense. That is, there will be holes in the zones where the two nearest defenders are farther apart from one another. For instance, if a cornerback is defending the outside third of the field and the safety is covering the middle, then the seam of the defense might be somewhere along the hash marks.
Teams try to disguise their zone coverages, hoping either the receiver or quarterback read the wrong coverage and therefore cannot find the seam in the defense. If they do so, a receiver might run to a spot on the field and wait for the quarterback to deliver the ball, knowing the defenders will not be there to deny the pass.
To give a better idea of coverages, let’s go into specific coverage packages.
Cover 0 Defense
Cover Zero defense is your standard man-to-man coverage. There are no double-teams in this coverage scheme. It is called Cover-0 because there are no safeties in deep coverage to make up for any mistakes by the cornerbacks. This play is often employed when a blitz is on; that is, when there are five or more defenders rushing the passer.
Cover 1 Defense
The Cover One defense uses one safety in deep coverage. This is a standard defensive scheme, where the free safety makes certain to keep receivers in front of him and help out the cornerback who needs the most help. This requires the free safety to make quick decisions and avoid being "looked off" by the quarterback. The free safety will often shade to one side of the field, where the opposing team’s best receiver is found.
The Cover 1 has the strong safety inch closer to the line, a process which is called "8 men in the box" (that is, a combination of 7 linemen and linebackers and 1 safety). Cover 1 is typically meant to stop the run, giving opportunities for the offense to pass instead.
Cover 2 Defense
The conventional Cover Two defense has both safeties back, with each covering one half of the field. The safeties cover deep, while the two cornerbacks cover the short routes on their side of the field.
Though all defenses employ Cover 2 defenses, some teams use this as their base defense. The most famous uses of the Cover 2 are the defenses employed by Tony Dungy with the Tampa Bay Buccaneers and the Indianapolis Colts.
Cover 2 schemes require safeties with better than average cover skills and cornerbacks with better than average tackling skills, because the corners will be asked to handle parts of the running game that a safety might normally handle. Also, the Cover 2 requires speedy linebackers who can get into coverage quickly.
The Cover 2 defense is a pass-oriented defense, because it uses only 7 men in the box. (I should not the "box" is an imaginary box along the defensive line of scrimmage. Those defenders in the box are thought to be the players allotted to stop the run instead of the pass.)
Cover 2 defenses typically employ smaller linebackers and safeties, the players most likely to tackle ball carriers. Therefore, given that the best tacklers are smaller and their is one less player in the box, the Cover 2 defense is sometimes thought to be weak against the run.
I’ve noticed that these defenses work splendidly when the defense’s team is ahead, because the offense will need to throw the ball more often. Conversely, if the defense is behind, it will need to stop the run more often, and therefore might wear down more quickly. This is a generalization, though, and it should be noted that all defenses will wear out if they must play from behind and stop the run more often.
It should also be noted the Cover 2 Defense is gaining wide acceptance in the NFL, because the Colts and Bucs have won Super Bowls using it and because the NFL rules changes have made offenses employ much more of a pass-first philosophy.
Cover 3 Defense
Cover Three defenses, the two cornerbacks join a safety in covering deep zones. These three players each cover their third of the field, while the other safety is moved into the box.
The Cover 3 defense does two things well. One, it stops the run, because the run blockers must account for an extra tackler. Two, it tends to stop the deep pass, because there are three defenders who are concentrating on keeping the receivers in front of them on the field.
Whatever this defense does not do well is cover short passes. With 8 men concentrating on the run and 3 men concentrating on the deep pass, this leaves wide open areas in the short routes. Therefore, an offense which reads the Cover 3 can check down to receivers underneath the three deep zone and move the ball slowly but methodically.
Cover 4 Defense
This is rare outside of two-minute and hurry-up situations. The Cover Four defense calls for both cornerbacks and both safeties (or some combination of four defensive backs) to cover deep zone. Essentially, the Cover 4 defense is a prevent defense, meant to give up running plays and short passing plays while ensuring against deep, quick scores.
The Prevent Defense is meant to trade time for field position. The defense will let the offense move down the field, though this takes time off the clock. Usually, the Cover 4 is used only when a defense is ahead in the game and they hope to run out the clock.
The Prevent Defense is often derided by football fans, because almost all teams employ the Cover 4 in these situations, and therefore late comebacks almost always take place against prevent defenses. Some fans say that prevent defenses prevent the team from winning the game.