In American football, a nickelback is a cornerback or safety who serves as the additional defensive back in a nickel defense. A base defense consists of two cornerbacks and two safeties, making the nickelback the fifth defensive back on the field, thus tying the name of the position to the name of the North American 5-cent piece.
Usually the nickelback will take the place of a linebacker, so if the team had been in a 4–3 formation, the four defensive linemen would remain, alongside only two linebackers and now-five defensive backs, creating a 4-2-5 formation. However, some teams will replace a lineman rather than a linebacker, creating a three linemen, three linebacker and five defensive back alignment, a 3–3–5 formation. If an offensive team always uses three or more wide receivers, a defense may turn to a nickel defense for their base package on most plays. Usually extra defensive backs, such as a nickelback, are substituted into the defense in situations where the opposing offense is likely to attempt a forward pass, such as 3rd-and-long, or when extra receivers are substituted into the opposing offense.
The nickelback is the third cornerback or safety on the depth chart. The nickelback is generally not considered a starting position because the starting formations for most defenses are either a 3-4 or a 4-3, in which only two cornerbacks and two safeties are utilized. Defensive formations with three or more cornerbacks (or three safeties) are used often enough that a nickelback will usually see moderate playing time (particularly in the modern, pass-oriented NFL) as well as subbing in for the starting corners. In certain packages (or if injuries depleted the depth chart), smaller free safeties or strong safeties can fill the spot of nickelback, as well. Their role may become that of a pass rusher from outside the box.
In Canadian football or CFL, where five defensive backs are considered the norm, the position is known as a defensive halfback.
In gridiron football, defensive backs (DBs), also called the secondary, are the players on the defensive side of the ball who play farthest back from the line of scrimmage. They are distinguished from the other two sets of defensive players, the defensive linemen who play directly on the line of scrimmage, and the linebackers, who play in the middle of the defense, between the defensive line and the defensive backs.
A cornerback (CB) is a member of the defensive backfield or secondary in gridiron football. Cornerbacks cover receivers most of the time, but also blitz and defend against such offensive running plays as sweeps and reverses. They create turnovers through hard tackles, interceptions, and deflecting forward passes.
In gridiron football, blitzing is a tactic used by the defense to disrupt pass attempts by the offense. During a blitz, a higher than usual number of defensive players will rush the opposing quarterback, in an attempt either to tackle him or force him to hurry his pass attempt.
Strategy forms a major part of American football. Both teams plan many aspects of their plays (offense) and response to plays (defense), such as what formations they take, who they put on the field, and the roles and instructions each player are given. Throughout a game, each team adapts to the other's apparent strengths and weaknesses, trying various approaches to outmaneuver or overpower their opponent in order to win the game.
American football positions have slowly evolved over the history of the sport. From its origins in early rugby football to the modern game, the names and roles of various positions have changed greatly, some positions no longer exist, and others have been created to fill new roles.
The 46 defense is an American football defensive formation, an eight men in the box defense, with six players along the line of scrimmage. There are two players at linebacker depth playing linebacker technique, and then three defensive backs. The 46 defense was originally developed and popularized with the Chicago Bears by their defensive coordinator Buddy Ryan, who later became head coach of the Philadelphia Eagles and Arizona Cardinals.
A formation in football refers to the position players line up in before the start of a down. There are both offensive and defensive formations and there are many formations in both categories. Sometimes, formations are referred to as packages.
In sports, a starting lineup is an official list of the set of players who will participate in the event when the game begins. The players in the starting lineup are commonly referred to as starters, whereas the others are substitutes or bench players.
In American football, a dimeback is a cornerback or safety who serves as the sixth defensive back on defense. The third cornerback or safety on defense is known as a nickelback. The dimeback position is essentially relegated to backup cornerbacks and safeties who do not play starting cornerback or safety positions. Dimebacks are usually fast players because they must be able to keep up on passing plays with 3+ wide receivers.
In American football, the specific role that a player takes on the field is referred to as their "position". Under the modern rules of American football, both teams are allowed 11 players on the field at one time and have "unlimited free substitutions", meaning that they may change any number of players during any "dead ball" situation. This has resulted in the development of three task-specific "platoons" of players within any single team: the offense, the defense, and the so-called 'special teams'. Within these three separate "platoons", various positions exist depending on the jobs that the players are doing.
There are several defensive formations commonly used in eight-man football. Defensive formations are classified by the total number of linemen and linebackers in the formation. The three basic types of formations in eight-man football are seven-man fronts, six-man fronts and five-man fronts.
In American football, a nickel defense is any defensive alignment that uses five defensive backs, of whom the fifth is known as a nickelback. The original and most common form of the nickel defense features four down linemen and two linebackers. Because the traditional 4–2 form preserves the defense's ability to stop an opponent's running game, it has remained more popular than its variants, to the extent that even when another formation technically falls within the "nickel" definition, coaches and analysts will refer to it by a more specific designation that conveys more information with equal or greater conciseness.
The prevent defense is a defensive alignment in American football that seeks to prevent the offense from completing a long pass or scoring a touchdown in a single play and seeks to run out the clock. It is used by a defense that is winning by more than a touchdown, late in the fourth quarter, or in specific situations, such as third-and-very-long if it seems clear that the offense must pass the football to gain long yardage.
In American football, the 3–4 defense is a common defensive alignment consisting of three down linemen and four linebackers. It is a called a "base defense" because it is the default defensive alignment used on "base downs". However, defenses will readily switch to other defensive alignments as circumstances change. Alternatively, some defenses use a 4–3 defense.
Zone coverage is a defense scheme in gridiron football used to protect against the pass.
The following terms are used in American football, both conventional and indoor. Some of these terms are also in use in Canadian football; for a list of terms unique to that code, see Glossary of Canadian football.
In American football, a back is a player who plays off of the line of scrimmage. Historically, the term "back" was used to describe multiple positions on offense and defense, although more descriptive and specific position naming is now common. Thus, "back" can refer to positions including:
In American football, the dime defense is a defensive alignment that uses six defensive backs. It is usually employed in obvious passing situations. The formation usually consists of six defensive backs, usually two safeties, and four cornerbacks, and has either four down linemen and one linebacker, or three down linemen and two linebackers. This formation is used to prevent the offense from completing a medium- to long-range pass play. This may be because the offense's running game is inefficient, time is an issue, or they need a long pass for a first down. It is also used against teams whose pass-to-run ratio predominantly favors pass. The formation, however, is vulnerable to running plays as the formation is missing two linebackers, or a linebacker and a down lineman.
In American football, an eight-in-the-box defense is a defensive alignment in which 8 of the 11 defensive players are close to the line of scrimmage.