Calling a defense is one of the greatest challenges in football. Game plans are based entirely on prediction—predicting what formations an offense will line up in, what sort of personnel they will use, and what sort of plays they will run. These predictions are based off of offensive tendencies.
Schemes are put in place to defend against a suspected offensive play, which differs by situation – an offense will have a different tendency on 1st and 10 than it will on 3rd and long. For example, the offense might have a tendency to throw deep on a 3rd and long situation. In that case, a defensive play will be called with deep routes in mind.
A coordinator will select fronts, coverages and pressure packages in hopes of stopping an offensive attack. The coordinator will then adjust the defensive scheme based on tendencies of the offense and adjustments made by the offense over the course of the game.
It is a strategic battle, back and forth, throughout the contest. To better understand this, the best place to start is at the beginning, or at the defensive Front, as it were.
The front is the first line of defense against an opposing offense. The players closest to the line of scrimmage are called—appropriately enough—defensive linemen. Slightly off the line of scrimmage, just behind the linemen, are the linebackers. They back up the linemen. The alignment of these players determines the defensive front.
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Traditional defensive fronts are named according to the number of defensive linemen, followed by the number of linebackers. The 3-4, for example, has three defensive linemen on the line of scrimmage and four linebackers behind them.
The 4-3 front has four defensive linemen and three linebackers. Defensive linemen in this front are commonly grouped into two categories: Defensive tackles and defensive ends. Defensive tackles are usually aligned somewhere from the outside shoulder of the center (which would be called a 1 technique) to the outside shoulder of the offensive guard (which would be called a 3 technique). The Defensive ends typically align anywhere from the inside shoulder of the offensive tackle to the outside shoulder of the tight end.
Coaches will often vary the alignments of the defensive linemen to confuse the offense's blocking schemes. A defensive scheme will often include the ability to shift from one front to another –shifting from a 3-4 to a 4-3 has become common practice, allowing a defense to bring another player down on the line of scrimmage.
Typical defensive fronts include:
- 4-3: 4 down linemen and 3 linebackers
- 3-4: 3 down linemen and 4 linebackers
- 5-2: 5 down linemen and 2 inside linebackers
- 3-3 Stack: 3 down linemen and 3 linebackers "stacked" immediately behind them
This is the standard and most common way to call a defensive front. That said, one should be wary of inventions that do not follow this standard, as they can throw off even experienced football fans. For example, the 46 defense, made popular by Chicago Bears' defensive coordinator Buddy Ryan during the 1985 championship season, has nothing to do with the alignment of players. The 46 defense was named after Doug Plank, who wore the jersey number 46—this was named after a style of play rather than a defensive alignment.
Defensive coverages are dictated by the assignments of the defensive backs. Linebackers have coverage responsibilities as well, but the schemes of the defensive backfield dictate the call. Man coverage, for example, is perhaps the most obvious: Defensive players match up man-to-man with offensive players.
Most coverages are identified by how the deepest part of the field will be defended. For example, a Cover 2 defense features two deep safeties, where each is responsible for their deep half of the field. Two people cover deep. In this case, the cornerbacks and linebackers divide up areas of the field closer to the line of scrimmage, with the two safeties serving as the last line of defense.
In Cover 4, the corners drop back and are responsible for a deep quarter of the field, along with the safeties. Now, the deepest part of the defense is divided into 4 parts, with each zone covered by a different player.
Typical defensive coverages include:
- 0/1: Man coverage with either 0 deep zone players, or 1 deep player (often referred to as 'man free')
- 2: the deepest part of the field is divided into 2 zones
- 3: the deepest part of the field is divided into 3 zones
- 4: the deepest part of the field is divided into 4 zones
Again, there are always adjustments to the rules as defensive and offensive coordinators try outsmart one another. For example, the Nickel defense is named so because a 5th defensive back is subbed into the game. This is usually an extra safety subbed in to cover a slot receiver or tight end, though they can be used in any number of ways. The pass-heavy modern offense has turned the Nickel defense into one of today's most common personnel packages.
A coordinator might also call a combo coverage, where more than one coverage strategy is used. Cover 3 Lock, as a completely hypothetical example, might include three deep players with the backside corner playing man coverage, "locked" on the backside receiver.
The combination of the Front and the Coverage creates the standard way of calling a defense. 4-3 Cover 2, for example, would feature 4 defensive linemen, 3 linebackers, and 2 safeties covering deep zones (with 2 cornerbacks covering "flat" zones underneath the deep coverage). Fronts and coverages have to be sound. Once they are, defensive coordinators can get creative and begin attacking an offense.
Stunts and Blitzes
Stunts and blitzes make up what many call "pressure" packages and add unpredictably to a defensive scheme. If a defense lines up the same way every time, an opposing offense will pick apart their predictable scheme. The answer to predictability is to stunt and blitz—move players around and attack the offense.
A stunt refers to some variation of a gap exchange using at least one defensive linemen. "Gap exchange" might sound like a complicated term, but it is fairly straightforward: The players in a defensive front are each assigned a gap to defend.
For example, a defensive tackle might be responsible for the B gap in a 4-3 alignment, while the defensive end is responsible for the C gap. In a gap exchange stunt, the defensive end might crash down into the B gap, while the defensive tackle loops around to the C gap. This stunt makes the offensive blocking assignments more difficult.
A blitz occurs when a linebacker or defensive back eschews their regular responsibilities and attacks the line of scrimmage as soon as the ball is snapped. If the middle linebacker in a 4-3 front is tabbed for a blitz, for example, they'll often attack the A gap:
This was originally intended to create a mismatch in numbers and again challenge the offense's blocking assignments. Blitzing can be risky. A linebacker might have to sacrifice his coverage zone in a passing situation. When called, the defensive coordinator is betting that the added pressure will be more valuable than the regular coverage.
A defensive scheme includes all components of a defense, choreographed in hopes of stopping an offensive tendency. On 1st and 10, if the offensive tendency is to run between the tackles, a coordinator might call 4-3 Cover 2, Wil A (in this case, Wil A would be the Weak Inside Linebacker blitzing through the A gap). This would fill almost every running lane on the snap of the ball.
On 3rd and 10, if the offensive tendency is to run between the tackles, a coordinator might call 3-4 Cover 4, dropping four players deep in coverage and rushing only three.
There is no right way to call a defensive. There is no single scheme to stop a specific play, especially since the defense will never know what offensive play has been called until the ball is snapped. The only choice a coordinator has is to be thoughtful in the construction of a defensive scheme.
Successful defensive schemes identify which front, coverage and pressure is best suited to stop an opposing offense.
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