Post by Coach Campbell on Apr 25, 2009 20:42:06 GMT
Basic pass coverage
Even in obvious running situations, the defense must be able to account for the eligible receivers on offense. There are two general schemes for defending against the pass:
Man-to-man, where each eligible receiver is covered by a defensive back or a linebacker.
Zone, where certain players (usually defensive backs or linebackers, though occasionally linemen as well) are assigned an area on the field that they are to cover.
In most cases, man-to-man coverage is more effective against short passes, while zone coverage is effective against long passes.
Advanced pass coverage
To create a shorthand, most defensive schemes use the term "cover" (for pass coverage) and a number to describe a combination of schemes. There are only five eligible pass receivers on a given play. The quarterback is technically eligible and would make six, but he cannot pass the ball to himself. In order to become a receiver, the quarterback must hand off or lateral to another player first, in effect making the new ball carrier the quarterback. In the NFL, the quarterback is ineligible for the entire play if he takes the snap from directly under center.
While there are at least seven pass defenders in 3-4 alignment in man-to-man defense, some of the pass coverage personnel may either blitz (cross the line of scrimmage with the down linemen in an attempt to sack the quarterback), provide double coverage on a receiver, or help other defensive players with the pass coverage. In zone coverage, all defensive linebackers and backs have a pass coverage assignment.
Cover One - Strict man-to-man (1 on 1) coverage with no help from safeties (usually a blitz play with at least five men crossing the line of scrimmage)
Cover One-Free - Man-to-man coverage with the free safety not assigned a man to cover, rather playing deep and reading the quarterback.
Cover Two - By far the most complicated zone coverage with the safeties playing deep and covering half the field each. In cover two the cornerbacks are considered to be "hard" corners, meaning that they have increased run stopping responsibilities and generally defend against shorter passes, although if two receivers run a deep route on a certain side of the field, that side's corner has deep coverage responsibility as well. It also relies heavily on the Mike (Middle) Linebacker's ability to quickly drop deep downfield into pass coverage when he reads pass. The advantage of cover 2 is that it provides great versatility to the defense as the corners can play run, short pass, and deep pass with the confidence that they have support from two deep safeties, while the disadvantage is that it leaves only 7 men in the "box" (area near the ball at the snap) to defend against the run. In contrast cover 1 and 3 usually leave 8 men in the box. A variant of cover two is the inverted cover 2, in which either right before or after the snap the corners "bail" out while the safeties come up - in effect switching responsibilities. This strategy may be employed to trick a quarterback who has not correctly interpreted the shift.
Cover Three - In cover three, the two corners and free safety each have responsibility for a deep third of the field, while the strong safety plays like a linebacker. This coverage is generally considered to be a run stopping defense as it focuses on preventing big pass plays and stopping the run while giving up short passes.
Cover Four - In cover four, each corner and safety is responsible for a deep quarter of the field (cover four is also sometimes referred to as "quarters"). This coverage is generally used as a prevent defense to be used near the end of a game or half, meaning that the defense sacrifices the run and short pass to avoid giving up the big play with the confidence that the clock will soon expire.
Other coverages
Bracket — A double team scheme to prevent a certain receiver from catching the ball. There are two types of bracket coverage: high/low and in/out.
High/low coverage involves one defensive player staying between the line of scrimmage and the receiver, protecting against short passes, and another defender playing behind the receiver to protect from deep routes.
Skilled personnel can beat this coverage, however, based on running a route that breaks to the inside. On an "in" route the receiver makes a near-90 degree turn to the inside of the field and uses his speed to get away from the underneath defender. A higher-difficulty option is the "post" or "skinny post" route, which involves a turn of 30-60 degrees to the inside. The receiver again uses his speed to separate from the defender playing underneath, and the quarterback must deliver the ball over this defender and far enough inside that the defender protecting against deep passes cannot come down/across the flight path of the ball and deflect or intercept it. Though the difficulty on this pass is much higher, its success will gain many more yards.
In/out coverage is a scheme where one defender protects against routes run to the inside and another protects against routes to the outside. The easiest way to beat this coverage is a simple "go"/streak route: the receiver simply sprints down the field past the defenders. Any hesitation on the defenders' part to drop their coverage assignment and run with the streaking receiver can be exploited.
Zone blitz — A play where a linebacker or defensive back blitzes and a lineman replaces him in pass coverage. The creation and refinement of this scheme is most often credited to Dick LeBeau while defensive coordinator for the Cincinnati Bengals and the Pittsburgh Steelers.
Bump-and-Run is a style of man-to-man defense with a more physical style. As modern offenses get more and more complex, one of their most important aspects becomes timing. Bump-and-Run coverage style takes advantage of this, jamming the receivers at the line and throwing off their routes' timing with their Quarterback. Bump-and-Run schemes require physical Corners with quick acceleration and good instincts. The biggest disadvantage to the Bump-and-Run is the high propensity of its Corners to commit fouls. As a result of the physical play required by the Bump-and-Run, its Corners get flagged much more often than Corners in other systems for penalties such as Illegal Hands to the Face, Illegal Contact, and the like. Additionally, Bump-and-Run coverage can sometimes give up deep passing plays if a Corner fails to jam his receiver at the line of scrimmage.
Strategy
Effective defense depends on cooperation of defensive players and an understanding of what coverage they are in. For example, in Cover Two, the cornerbacks know that if they decide to jump a route (and thereby intercept or deflect a pass) they will have safety help further upfield should they be tricked by a fake. In Cover One, the safety must be aware that one of the cornerbacks could have difficulty covering a wide receiver, and must be available to move over to help the cornerback before the quarterback can throw. Typically Cover One is only used if there are more than two wide receivers or other passing threats.
Moreover, mixing up defensive alignments and not being predictable are important since if an offense recognizes an alignment or coverage scheme, or a tendency to use such a scheme, they can often take advantage of it. For example, if the defense is blitzing, and the quarterback foresees it (for example, one of the blitzing players moves towards the line of scrimmage before the snap) the quarterback knows he faces man-to-man coverage and will look for his fastest receiver to get open, or throw to the spot vacated by the blitzing player.
Special Cases
In the modern game, with players getting faster and stronger, defensive coordinators often look to a player's special skills in order to surprise the offense. For example, in some defensive schemes, defensive down linemen are given pass coverage responsibility. Since Lawrence Taylor's arrival, teams often now rush three down linemen and a single linebacker (often a different one on every play), a strategy that was almost unknown before he started to play. Moreover, even defensive backs are being given more responsibility on running plays. For example, on plays where a running back runs wide, it is the responsibility of the cornerback to ensure that the running back does not get directly to the sideline, and that the back is forced to run in front of the cornerback where there is more likely to be help from linebackers.
Modern offenses have adapted to these strategies, and often require different skills from players, particularly running backs who, in addition to carrying the ball, are expected to run deep pass routes against linebacker coverage, and to be available to block blitzing players on pass plays.
Even in obvious running situations, the defense must be able to account for the eligible receivers on offense. There are two general schemes for defending against the pass:
Man-to-man, where each eligible receiver is covered by a defensive back or a linebacker.
Zone, where certain players (usually defensive backs or linebackers, though occasionally linemen as well) are assigned an area on the field that they are to cover.
In most cases, man-to-man coverage is more effective against short passes, while zone coverage is effective against long passes.
Advanced pass coverage
To create a shorthand, most defensive schemes use the term "cover" (for pass coverage) and a number to describe a combination of schemes. There are only five eligible pass receivers on a given play. The quarterback is technically eligible and would make six, but he cannot pass the ball to himself. In order to become a receiver, the quarterback must hand off or lateral to another player first, in effect making the new ball carrier the quarterback. In the NFL, the quarterback is ineligible for the entire play if he takes the snap from directly under center.
While there are at least seven pass defenders in 3-4 alignment in man-to-man defense, some of the pass coverage personnel may either blitz (cross the line of scrimmage with the down linemen in an attempt to sack the quarterback), provide double coverage on a receiver, or help other defensive players with the pass coverage. In zone coverage, all defensive linebackers and backs have a pass coverage assignment.
Cover One - Strict man-to-man (1 on 1) coverage with no help from safeties (usually a blitz play with at least five men crossing the line of scrimmage)
Cover One-Free - Man-to-man coverage with the free safety not assigned a man to cover, rather playing deep and reading the quarterback.
Cover Two - By far the most complicated zone coverage with the safeties playing deep and covering half the field each. In cover two the cornerbacks are considered to be "hard" corners, meaning that they have increased run stopping responsibilities and generally defend against shorter passes, although if two receivers run a deep route on a certain side of the field, that side's corner has deep coverage responsibility as well. It also relies heavily on the Mike (Middle) Linebacker's ability to quickly drop deep downfield into pass coverage when he reads pass. The advantage of cover 2 is that it provides great versatility to the defense as the corners can play run, short pass, and deep pass with the confidence that they have support from two deep safeties, while the disadvantage is that it leaves only 7 men in the "box" (area near the ball at the snap) to defend against the run. In contrast cover 1 and 3 usually leave 8 men in the box. A variant of cover two is the inverted cover 2, in which either right before or after the snap the corners "bail" out while the safeties come up - in effect switching responsibilities. This strategy may be employed to trick a quarterback who has not correctly interpreted the shift.
Cover Three - In cover three, the two corners and free safety each have responsibility for a deep third of the field, while the strong safety plays like a linebacker. This coverage is generally considered to be a run stopping defense as it focuses on preventing big pass plays and stopping the run while giving up short passes.
Cover Four - In cover four, each corner and safety is responsible for a deep quarter of the field (cover four is also sometimes referred to as "quarters"). This coverage is generally used as a prevent defense to be used near the end of a game or half, meaning that the defense sacrifices the run and short pass to avoid giving up the big play with the confidence that the clock will soon expire.
Other coverages
Bracket — A double team scheme to prevent a certain receiver from catching the ball. There are two types of bracket coverage: high/low and in/out.
High/low coverage involves one defensive player staying between the line of scrimmage and the receiver, protecting against short passes, and another defender playing behind the receiver to protect from deep routes.
Skilled personnel can beat this coverage, however, based on running a route that breaks to the inside. On an "in" route the receiver makes a near-90 degree turn to the inside of the field and uses his speed to get away from the underneath defender. A higher-difficulty option is the "post" or "skinny post" route, which involves a turn of 30-60 degrees to the inside. The receiver again uses his speed to separate from the defender playing underneath, and the quarterback must deliver the ball over this defender and far enough inside that the defender protecting against deep passes cannot come down/across the flight path of the ball and deflect or intercept it. Though the difficulty on this pass is much higher, its success will gain many more yards.
In/out coverage is a scheme where one defender protects against routes run to the inside and another protects against routes to the outside. The easiest way to beat this coverage is a simple "go"/streak route: the receiver simply sprints down the field past the defenders. Any hesitation on the defenders' part to drop their coverage assignment and run with the streaking receiver can be exploited.
Zone blitz — A play where a linebacker or defensive back blitzes and a lineman replaces him in pass coverage. The creation and refinement of this scheme is most often credited to Dick LeBeau while defensive coordinator for the Cincinnati Bengals and the Pittsburgh Steelers.
Bump-and-Run is a style of man-to-man defense with a more physical style. As modern offenses get more and more complex, one of their most important aspects becomes timing. Bump-and-Run coverage style takes advantage of this, jamming the receivers at the line and throwing off their routes' timing with their Quarterback. Bump-and-Run schemes require physical Corners with quick acceleration and good instincts. The biggest disadvantage to the Bump-and-Run is the high propensity of its Corners to commit fouls. As a result of the physical play required by the Bump-and-Run, its Corners get flagged much more often than Corners in other systems for penalties such as Illegal Hands to the Face, Illegal Contact, and the like. Additionally, Bump-and-Run coverage can sometimes give up deep passing plays if a Corner fails to jam his receiver at the line of scrimmage.
Strategy
Effective defense depends on cooperation of defensive players and an understanding of what coverage they are in. For example, in Cover Two, the cornerbacks know that if they decide to jump a route (and thereby intercept or deflect a pass) they will have safety help further upfield should they be tricked by a fake. In Cover One, the safety must be aware that one of the cornerbacks could have difficulty covering a wide receiver, and must be available to move over to help the cornerback before the quarterback can throw. Typically Cover One is only used if there are more than two wide receivers or other passing threats.
Moreover, mixing up defensive alignments and not being predictable are important since if an offense recognizes an alignment or coverage scheme, or a tendency to use such a scheme, they can often take advantage of it. For example, if the defense is blitzing, and the quarterback foresees it (for example, one of the blitzing players moves towards the line of scrimmage before the snap) the quarterback knows he faces man-to-man coverage and will look for his fastest receiver to get open, or throw to the spot vacated by the blitzing player.
Special Cases
In the modern game, with players getting faster and stronger, defensive coordinators often look to a player's special skills in order to surprise the offense. For example, in some defensive schemes, defensive down linemen are given pass coverage responsibility. Since Lawrence Taylor's arrival, teams often now rush three down linemen and a single linebacker (often a different one on every play), a strategy that was almost unknown before he started to play. Moreover, even defensive backs are being given more responsibility on running plays. For example, on plays where a running back runs wide, it is the responsibility of the cornerback to ensure that the running back does not get directly to the sideline, and that the back is forced to run in front of the cornerback where there is more likely to be help from linebackers.
Modern offenses have adapted to these strategies, and often require different skills from players, particularly running backs who, in addition to carrying the ball, are expected to run deep pass routes against linebacker coverage, and to be available to block blitzing players on pass plays.