Football coverage shells
Encyclopedia
In American football
, coverage shells describe the alignment and responsibilities of defensive back
s.
In passing situations, the defense will assign players to guard portions of the field, forming a defensive "shell" that the defense hopes will either prevent the offense from completing a pass or ensure a defensive player is able to tackle the receiver after a completed pass. The general terminology used to describe this alignment is "Cover #," with "#" being the number of defensive players forming the coverage shell.
alignment where each defensive back covers one receiver.
a receiver if needed.
from various pre-snap formations while engaging in complex man-to-man coverage schemes post-snap. For example, a safety may blitz while a cornerback
is locked in man coverage with a receiver. Or the cornerback may blitz with the safety rotating into man coverage on the receiver post-snap.
A secondary weakness is inherent in its design: the use of man coverage opens up yards after catch lanes. Man coverage is attacked by offenses in various ways that try to isolate their best athletes on defenders by passing them the ball quickly before the defender can react or designing plays that clear defenders from certain areas thus opening yards after catch lanes.
, Minnesota Vikings
, Chicago Bears
, and Detroit Lions
all run or have run a variant of this defense called the Tampa 2
. In the Tampa 2 defense, a third player (usually the middle linebacker
) plays a middle zone, guarding an area closer to the line of scrimmage than the safeties but farther out from typical "underneath" pass coverages.
Cover 2 can be run from any seven-man defensive front such as the 3-4
and the 4-3
defenses. Various kinds of "underneath" coverages played by cornerbacks and linebackers may also be implemented. For example, "Cover 2 Man" means the two safeties have deep coverage responsibility while the cornerbacks and linebackers follow their offensive assignment in one-on-one coverage. The San Diego Chargers
inherited a base Cover 2 Man 3-4 from former coach Wade Phillips
. Cover 2 can also be paired with underneath zone schemes: "Cover 2 Zone" refers to two safeties with deep coverage responsibility, but now the cornerbacks and linebackers drop into specific coverage zones where they defend passes only in their assigned area.
In cover 2 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.
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.
The main drawback is that the middle of the field is left open, a disadvantage that allowed Larry Fitzgerald
to score a touchdown in Super Bowl XLIII
against the Steelers.
) into the hole, the offense forces the safety to make a decision: play the vulnerable hole in the middle of the field or help out on the wide receiver. The quarterback reads the safety's decision and decides on the best matchup (i.e. which mismatch is better: tight end vs. safety or wide receiver vs. cornerback).
Another disadvantage of Cover 2 is that it leaves only seven men in the "box" (the area near the ball at the snap) to defend against the run. In contrast Cover 1 and Cover 3 usually leave eight men in the box.
A potential problem with the Cover 2 is that defensive pressure on the Quarterback must be provided nearly exclusively by the front linemen as all other defenders are involved in pass coverage. If the defensive linemen do not provide adequate pressure on the Quarterback, the offense is afforded plenty of time to create and exploit passing opportunities. Blitzing in the Cover 2 often creates greater areas of weakness in the defense than other coverages. Thus, unsuccessful blitzes can prove to be more productive for the offense than in other schemes.
On the snap, the CBs work for depth, backpedaling into their assigned zone. One safety moves toward the center of the field. The other safety is free to rotate into the flat area (about 2-4 yards beyond the line of scrimmage), provide pass coverage help, or blitz.
Another disadvantage of cover 3 schemes is they are relatively easy to diagnose by opposing quarterbacks. Because of this, teams will often employ slight wrinkles in their coverage to confuse offenses. An example of this includes employing man coverage on one side and zone on another or swapping coverage zones between defenders.
).
The most basic Cover 4 scheme involves two cornerbacks and two safeties. Upon snap, the cornerbacks work for depth, backpedaling into their assigned zone. Both safeties backpedal towards their assigned zone.
As with other coverage shells, Cover 4 is paired with underneath man or zone coverage in its most basic form.
Cover 4 also has the advantage of using safeties in run support as opposed to cornerbacks as would be the case in a Cover 2 scheme. This gives the defense nine in the box and the ability to stop the run with an extra defender on either side. The play-side safety would come up in support on a running play while the back-side safety would be responsible for the middle third of the field and the cornerbacks would have the deep outside thirds.
, call offensive strength to the Field instead of to the offensive formation or front, and organize personnel by Field-side player and Boundary-side player. The position of the ball on the field therefore dictates strength of the offense. In Cover 6 the field safety and field corner cover fourths of the field, and depend on a field outside linebacker to support underneath them. The free safety covers the boundary-side deep half and the boundary corner plays the flat. Thus the field side of the coverage is quarters, and the boundary side is cover 2.
The Cover 6 gets its name from the fact that it combines elements of the Cover 2 (the strong safety covering half the field) and the Cover 3 (the use of three deep zone defenders). The Pittsburgh Steelers
are a Cover 6 team. The quarters play of the strong side safety, like the Steelers' Troy Polamalu, allows him to support on runs quickly. The Tennessee Titans
have also been known to use it.
American football
American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...
, coverage shells describe the alignment and responsibilities of defensive back
Defensive back
In American football and Canadian football, defensive backs are the players on the defensive team who take positions somewhat back from the line of scrimmage; they are distinguished from the defensive line players and linebackers, who take positions directly behind or close to the line of...
s.
In passing situations, the defense will assign players to guard portions of the field, forming a defensive "shell" that the defense hopes will either prevent the offense from completing a pass or ensure a defensive player is able to tackle the receiver after a completed pass. The general terminology used to describe this alignment is "Cover #," with "#" being the number of defensive players forming the coverage shell.
Cover 0
Cover 0 is a strict man-to-manMan-to-man defense
Man-to-man defense is a type of defensive tactic used in American football, association football, and basketball in which each player is assigned to defend and follow the movements of a single player on offense. Often, a player guards his counterpart , but a player may be assigned to guard a...
alignment where each defensive back covers one receiver.
Advantages
Cover 0 is an aggressive scheme that allows for numerous blitz packages, as it's easier for players to drop off their coverage and rush the quarterback.Disadvantages
The main disadvantage of Cover 0 is that there is no "help over the top" - if a wide receiver "beats" (runs past) his defender, there is no one left in the secondary who can make up the coverage on the receiver, which could result in an easy pass completion and possible touchdown.Cover 1
Cover One is a man-to-man coverage for all the defensive backs except for one player (usually a safety) who is not assigned a man to cover but rather plays deep and reacts to the development of the play. Often the safety will remain in a pass coverage position and play a zone defense by guarding the middle of the backfield, reacting to runs or completed passes and double-teamingDouble team
In basketball, a double team is a defensive alignment in which two defensive players are assigned to guard a single offensive player....
a receiver if needed.
Advantages
Cover 1 schemes are usually very aggressive, preferring to proactively disrupt the offense by giving the quarterback little time to make a decision while collapsing the pocket quickly. This is the main advantage of Cover 1 scheme - the ability to blitzBlitz (American football)
In American football or Canadian football, a blitz or red dog is when players on or behind the line of scrimmage during a play, are sent across the scrimmage line to the offensive side to try to tackle the quarterback or disrupt his pass attempt...
from various pre-snap formations while engaging in complex man-to-man coverage schemes post-snap. For example, a safety may blitz while a cornerback
Cornerback
A cornerback is a member of the defensive backfield or secondary in American and Canadian football. Cornerbacks cover receivers, to defend against pass offenses and make tackles. Other members of the defensive backfield include the safeties and occasionally linebackers. The cornerback position...
is locked in man coverage with a receiver. Or the cornerback may blitz with the safety rotating into man coverage on the receiver post-snap.
Disadvantages
The main weakness of the Cover 1 scheme is that there is only one deep defender that must cover a large amount of field and provide help on any deep threats. Offenses can attack Cover 1 schemes by sending two receivers on deep routes, provided that the quarterback has enough time for his receivers to get open. The deep defender must decide which receiver to help out on, leaving the other in man coverage which may be a mismatch.A secondary weakness is inherent in its design: the use of man coverage opens up yards after catch lanes. Man coverage is attacked by offenses in various ways that try to isolate their best athletes on defenders by passing them the ball quickly before the defender can react or designing plays that clear defenders from certain areas thus opening yards after catch lanes.
Cover 2
In traditional Cover 2 schemes the free safety (FS) and strong safety (SS) have deep coverage responsibilities, each guarding half of the field. The Tampa Bay BuccaneersTampa Bay Buccaneers
The Tampa Bay Buccaneers are a professional American football franchise based in Tampa, Florida, U.S. They are currently members of the Southern Division of the National Football Conference in the National Football League – they are the only team in the division not to come from the old NFC West...
, Minnesota Vikings
Minnesota Vikings
The Minnesota Vikings are a professional American football team based in Minneapolis, Minnesota. The Vikings joined the National Football League as an expansion team in 1960...
, Chicago Bears
Chicago Bears
The Chicago Bears are a professional American football team based in Chicago, Illinois. They are members of the North Division of the National Football Conference in the National Football League...
, and Detroit Lions
Detroit Lions
The Detroit Lions are a professional American football team based in Detroit, Michigan. They are members of the North Division of the National Football Conference in the National Football League , and play their home games at Ford Field in Downtown Detroit.Originally based in Portsmouth, Ohio and...
all run or have run a variant of this defense called the Tampa 2
Tampa 2
The Tampa 2 is an American football defensive strategy popularized by the Tampa Bay Buccaneers National Football League team in the mid 1990s-early 2000s. The Tampa 2 is typically employed out of a 4-3 defensive alignment, which consists of four linemen, three linebackers, two cornerbacks, and...
. In the Tampa 2 defense, a third player (usually the middle linebacker
Linebacker
A linebacker is a position in American football that was invented by football coach Fielding H. Yost of the University of Michigan. Linebackers are members of the defensive team, and line up approximately three to five yards behind the line of scrimmage, behind the defensive linemen...
) plays a middle zone, guarding an area closer to the line of scrimmage than the safeties but farther out from typical "underneath" pass coverages.
Cover 2 can be run from any seven-man defensive front such as the 3-4
3-4 defense
In American football, the 3–4 defense is a defensive alignment consisting of three down linemen and four linebackers.The 3–4 defense declined in popularity over the years, but has found renewed use by modern professional and college football teams. The 3–4 defense is so named because it involves 3...
and the 4-3
4-3 defense
In American football, a 4–3 defense is a defensive alignment consisting of four down linemen and three linebackers. It is probably the most commonly used defense in modern American football and especially in the National Football League. NFL teams that use the 4–3 defense as of 2011 include the...
defenses. Various kinds of "underneath" coverages played by cornerbacks and linebackers may also be implemented. For example, "Cover 2 Man" means the two safeties have deep coverage responsibility while the cornerbacks and linebackers follow their offensive assignment in one-on-one coverage. The San Diego Chargers
San Diego Chargers
The San Diego Chargers are a professional American football team based in San Diego, California. they were members of the Western Division of the American Football Conference in the National Football League...
inherited a base Cover 2 Man 3-4 from former coach Wade Phillips
Wade Phillips
Wade Allen Phillips is the defensive coordinator for the Houston Texans and former head coach for the National Football League's Dallas Cowboys, Denver Broncos, and Buffalo Bills. He was also an interim head coach for the New Orleans Saints and Atlanta Falcons...
. Cover 2 can also be paired with underneath zone schemes: "Cover 2 Zone" refers to two safeties with deep coverage responsibility, but now the cornerbacks and linebackers drop into specific coverage zones where they defend passes only in their assigned area.
In cover 2 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.
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.
The main drawback is that the middle of the field is left open, a disadvantage that allowed Larry Fitzgerald
Larry Fitzgerald
Larry Darnell Fitzgerald, Jr. is an American football wide receiver for the Arizona Cardinals of the National Football League, and currently ranks fourth all-time in league history in receiving yards per game for a career , behind Andre Johnson, Torry Holt, and Marvin Harrison...
to score a touchdown in Super Bowl XLIII
Super Bowl XLIII
Super Bowl XLIII was an American football game pitting the American Football Conference champion Pittsburgh Steelers against the National Football Conference champion Arizona Cardinals to decide the National Football League champion for the 2008 season. The game was played on February 1, 2009,...
against the Steelers.
Advantages
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.Disadvantages
The main weakness of the Cover 2 shell occurs in the middle of the field between the safeties. At the snap of the ball, many times the safeties will move toward the sidelines in order to cover any long passes to quick wide receivers. This movement creates a natural hole between the safeties that can be attacked. By sending a receiver (usually a tight endTight end
The tight end is a position in American football on the offense. The tight end is often seen as a hybrid position with the characteristics and roles of both an offensive lineman and a wide receiver. Like offensive linemen, they are usually lined up on the offensive line and are large enough to be...
) into the hole, the offense forces the safety to make a decision: play the vulnerable hole in the middle of the field or help out on the wide receiver. The quarterback reads the safety's decision and decides on the best matchup (i.e. which mismatch is better: tight end vs. safety or wide receiver vs. cornerback).
Another disadvantage of Cover 2 is that it leaves only seven men in the "box" (the area near the ball at the snap) to defend against the run. In contrast Cover 1 and Cover 3 usually leave eight men in the box.
A potential problem with the Cover 2 is that defensive pressure on the Quarterback must be provided nearly exclusively by the front linemen as all other defenders are involved in pass coverage. If the defensive linemen do not provide adequate pressure on the Quarterback, the offense is afforded plenty of time to create and exploit passing opportunities. Blitzing in the Cover 2 often creates greater areas of weakness in the defense than other coverages. Thus, unsuccessful blitzes can prove to be more productive for the offense than in other schemes.
Cover 3
In cover 3, 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.On the snap, the CBs work for depth, backpedaling into their assigned zone. One safety moves toward the center of the field. The other safety is free to rotate into the flat area (about 2-4 yards beyond the line of scrimmage), provide pass coverage help, or blitz.
Advantages
One of the biggest benefits of the cover 3 coverage scheme is the ability to walk the strong safety up into the box with minimal to no changes in the coverage due to the pre-snap center field position of the free safety. This enables the defense to play both man and zone coverage out of an 8 man front while cover 2 schemes allow only for man coverage with 8 man fronts.Disadvantages
Cover 3 schemes are susceptible to short, timed passes to the outside due to the hard drop of both cornerbacks. This puts pressure on the outside linebackers to react to pass plays and get into their drop quickly if they need to cover a receiver.Another disadvantage of cover 3 schemes is they are relatively easy to diagnose by opposing quarterbacks. Because of this, teams will often employ slight wrinkles in their coverage to confuse offenses. An example of this includes employing man coverage on one side and zone on another or swapping coverage zones between defenders.
Cover 4
Cover 4 refers to four deep defenders, each guarding one-fourth of the deep zone. Cover 4 schemes are usually used to defend against deep passes. (See Prevent defensePrevent defense
Prevent defense is an American football defensive alignment that uses seven or more defensive backs or players in a defensive back role, the goal of which is to prevent the opposing offense from completing a long pass...
).
The most basic Cover 4 scheme involves two cornerbacks and two safeties. Upon snap, the cornerbacks work for depth, backpedaling into their assigned zone. Both safeties backpedal towards their assigned zone.
As with other coverage shells, Cover 4 is paired with underneath man or zone coverage in its most basic form.
Advantages
The main advantage of a Cover 4 defense is that it is extremely difficult for even the best quarterbacks to complete long passes against it. Therefore, 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.Cover 4 also has the advantage of using safeties in run support as opposed to cornerbacks as would be the case in a Cover 2 scheme. This gives the defense nine in the box and the ability to stop the run with an extra defender on either side. The play-side safety would come up in support on a running play while the back-side safety would be responsible for the middle third of the field and the cornerbacks would have the deep outside thirds.
Disadvantages
The main weakness of Cover 4 shells is the large amount of space left open by the retreating defensive backs. Since the defensive backs are working for depth, short pass routes underneath can enable the quarterback to make short- and medium- length passes, as well as isolate a defensive back on a wide receiver near the sideline with little help.Cover 6
Cover 6 refers to three deep defenders. However, unlike the 'Cover 3', the field is not split equally. Most teams that use Cover 6 are 3-4 Defenses3-4 defense
In American football, the 3–4 defense is a defensive alignment consisting of three down linemen and four linebackers.The 3–4 defense declined in popularity over the years, but has found renewed use by modern professional and college football teams. The 3–4 defense is so named because it involves 3...
, call offensive strength to the Field instead of to the offensive formation or front, and organize personnel by Field-side player and Boundary-side player. The position of the ball on the field therefore dictates strength of the offense. In Cover 6 the field safety and field corner cover fourths of the field, and depend on a field outside linebacker to support underneath them. The free safety covers the boundary-side deep half and the boundary corner plays the flat. Thus the field side of the coverage is quarters, and the boundary side is cover 2.
The Cover 6 gets its name from the fact that it combines elements of the Cover 2 (the strong safety covering half the field) and the Cover 3 (the use of three deep zone defenders). The Pittsburgh Steelers
Pittsburgh Steelers
The Pittsburgh Steelers are a professional football team based in Pittsburgh, Pennsylvania. The team currently belongs to the North Division of the American Football Conference in the National Football League . Founded in , the Steelers are the oldest franchise in the AFC...
are a Cover 6 team. The quarters play of the strong side safety, like the Steelers' Troy Polamalu, allows him to support on runs quickly. The Tennessee Titans
Tennessee Titans
The Tennessee Titans are a professional American football team based in Nashville, Tennessee, United States. They are members of the South Division of the American Football Conference in the National Football League . Previously known as the Houston Oilers, the team began play in 1960 as a charter...
have also been known to use it.