As we begin to look at the defensive side of the ball it is important to remember that defenses are designed to stop offenses, therefore each different defensive coach is going to have different ideas as to how to stop offensive ideas.
As you will learn as we take our little journey, the idea of different offensive and defensive “systems” in the NFL that analysts talk so much about is highly misunderstood. The idea of a system doesn’t refer to using completely different ideas than any one else, it is merely a difference in what is emphasized and what the base plays might be from one team to the next. Overall the teams are running most of the same things, just emphasizing different ideas or plays.
With this in mind we dive into the defensive side of the ball. On defense there are 3 main position groups. The linemen, the line backers and the secondary or defensive backs. In almost every defense the secondary positions are the same, however the use of linemen and line backers can vary.
There are two schools of thought concerning the use of the defensive line and linebackers, the first is using 4 defensive linemen, and 3 linebackers, this is referred to as a 4-3 defense. The second is using 3 defensive linemen, and 4 linebackers, this is called the 3-4 defense (I’m always amazed at the creativity that is used in these names!).
First we will look at the positions used in a 4-3 defense.
Defensive End (E or DE)-Pretty basic, he lines up on the either end of the defensive line, with one hand on the ground in what is called a 3 point stance.
Defensive Tackle (N or T)- These players line up inside of the DE in a 3 point stance. The one closest to the offense’s center is usually referred to as a Nose tackle (N).
Linebackers (S, M, W)- These players line up in a 2 point stance several yards behind the defensive line. S refers to the strong side or Sam backer, M refers to the middle or Mike backer, and W refers to the weak side or Will backer.
Cornerbacks (C or CB)- These players line up in 2 point stances at different depths across for the offenses WR’s.
Safeties (SS, FS)- These players line up in a 2 point stance anywhere from 8 to 15 yards behind the defensive line. The Free Safety (FS) lines up on the weak side, while the Strong Safety (SS) lines up on the weak side.
Now that we have looked at the 4-3 defense we will look at the 3-4 defense.
As you can tell the main difference as far as personnel is concerned is the fact that one of the Defensive Tackles has been replaced by a second Mike linebacker.
As we learned in our Offensive basics post, we know that offenses will attempt to gain an advantage by changing personnel groupings. Most times defenses will counter these moves by changing personnel of their own. There are two very common adjustments to personnel that defensive coaches make, the Nickel and the Dime packages.
The Nickel package features the replacement of either a LB or a Defensive Lineman with another Defensive back, usually a CB. Putting 5 DB’s on the field. This extra DB is known as the Nickel Back (N)
The dime package features a 2nd LB or D-Linemen being removed from the game and replaced by a DB know as the Dime back(D). This puts 6 DB’s on the field.
Now that we know the basics of defensive personnel, we can take a look tomorrow at common run plays used by Offenses, and common pass coverages used by Defenses.