In the A gap between center and guard, a 1 technique player aligns crosswise from either shoulder of the center (a technique also known as shadowing). The defender is in charge of closing the gap and should be able to handle a double-team by the center and guard. In a 4-3 system, the 1 method is widely utilized. It is used by both the defensive tackle and the three-technique defensive end who each seek to get the center on their side of the field.
In the B gap between left guard and right guard, a 1 technique player will align head up with the guard. The defender is responsible for any backside pursuit. If the backside guard goes down, the 1 technique player must fill that hole. At the next level of the field, there are two players positioned here: one on the line playing the A gap role described above and one playing the B gap role. These are referred to as "1-on-1" defenders because they're alone against an offensive lineman. They need to be aware of what's going on around them and play the ball.
At the next level of the field are pairs of players aligned in the C gap. Here, one player is assigned to each gap. Their job is to make sure that nobody gets through their area of the field. For example, if the offense runs a sweep action to the right, the left defensive tackle must be prepared to stop the play.
The 2 technique is an alignment and technique designation for an interior defensive lineman who is positioned head up over an offensive guard on the line of scrimmage. The two-technique defender is responsible for managing both the A Gap and the B Gap in most defensive schemes, making him a two-gap player. Because of this, he typically plays either the 1st or 3rd downline position.
Two-gapping was originally used by Bear Bryant as a way to account for the fact that most guards were then played on the outside shoulder of their respective tackles. This allowed him to have his nose tackle play the 2-gap role, which is why this technique is also called "the nose" technique.
In more recent years, several coaches have moved away from playing their nose tackle in this manner because it limits their ability to stunt or loop the end around the outside. Instead, they will have him stand up and play the one-gap center position while still having a hand placed inside the guard's face mask. This allows them to use more varied tactics on the field and gives them a better opportunity at stopping the run with just four players.
While two-gapping was initially developed to be used by college football teams, today it is commonly seen in the NFL.
When a defender is confronted with a tackle, he is in a 4 technique. A 6 method is used when the defender is situated straight across from the tight end. The number indicates how many players are blocking him.
There are two ways to block a 6 technique: a down lineman or an off-line blocker. An off-line blocker will fill the gap left by the defensive player and then push him outside where another offensive player is waiting to block him.
The advantage of using an off-line blocker is that it keeps the defense guessing on whether they should focus their attention on the off-line blocker or the downlineman. This can cause them to make mistakes.
Using a downlineman to block a 6 technique is much more predictable. The offense knows what kind of block they are going to get so they can plan for it. This means that the downlinemen have better odds of making the play.
Here is an example of a 6 technique. Say that the quarterback drops back to pass and there is no free receiver. One of the linemen would be able to block this defender if both of them wanted to. They would pull and lead with their arms, creating a hole for their teammate to run through.
As you can see, a 3 technique is a defensive lineman who often sets up on a guard's outside shoulder. A defensive lineman who uses the A-5 technique often positions up on the outside shoulder of the offensive tackle. The A-5 is most effective at stopping the run because it prevents the offensive line from pulling together and forming a wall against which the defense can rush the quarterback.
The A-5 is used primarily by 4-3 defenses to stop the run. However, some 3-4 teams may use an A-5 player when they want to put more pressure on the quarterback. Because there are more players aligned along the line of scrimmage, the A-5 is less likely to be blocked out of position by a running back than other techniques are. Instead, the A-5 defender tends to stay with his assigned running back all the way until the ball is carried away from him. At that point, he can flow back into the play if necessary.
A defensive end using the A-5 technique sets up about three inches outside the left edge of the offensive line. His goal is to stop the run by taking away any holes created by the guards. Since the A-5 player is usually not involved in pass protection, he needs to be strong enough to handle double teams. This means he should play on the smaller side (less than 300 pounds).