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Football 101 – 4-3 Defense

“Football 101” is a series by Joel Bishop that will take an in-depth look at formations, coverages, passing concepts and much more to give fans a better knowledge and understanding of the game.


The 4-3 defensive front has four defensive lineman and three linebackers (hence the name 4-3) using a one-gap scheme.

Before I go into detail on the different 4-3 fronts, let’s take a look at the individual positions.

Defensive Line

Weak-side and strong-side defensive ends

3-technique defensive tackle

Nose tackle (will align 0-shade, 1-technique, 2i-technique)


Weak-side linebacker “Will”

Middle linebacker “Mike”

Strong-side linebacker “Sam”


Now we know the individual positions, we can look at the different fronts.

4-3 Under Front


The easiest way to identify the difference between “over” and “under” is the alignment of the defensive tackles. In the “under” front, the 3-technique is aligned to the weak-side of the play and the nose tackle is aligned to the strong-side. Above is the Tampa Bay Buccaneers in their 4-3 “under” front. Highlighted by a red circle is Gerald McCoy playing at the 3-technique position and aligned to the weak-side, the defensive tackle highlighted with a blue circle is playing at the 1-technique spot. The linebacker with ‘W’ written above him is the “Will/weak-side” linebacker, ‘M’ for “Mike/middle” and ‘S’  for “Sam/strong-side”. As you see each player has a single gap to cover in the run game for the 4-3 scheme.


4-3 Over Front


Here is the 4-3 “over” front, similar to the “under” front but this time the 3-technique (highlighted by the red circle) is aligned to the strong-side and the nose tackle playing the 1-technique (highlighted with a blue circle) is on the weak-side. The linebackers in this front are aligned in a “tan-zero-tan” look (tackle-zero technique-tackle). As you see with the arrows, this is their gap responsibility against the run.


4-3 Wide-9


The term “wide-9” comes from the alignment of the defensive ends (highlighted by a yellow circle) at the 9-technique, the very furthest away from the core of the formation. A team that align in a “wide-9” a lot is the Detroit Lions. The Lions are using an “over” front, the 3-technique (highlighted by a red circle) is on the strong-side and the nose (highlighted by a blue circle) is aligned as a 2i-technique (inside shoulder of guard) which is common using “wide-9”. Just like an ordinary “over” front, the linebackers are in their “tan-zero-tan” look.


  1. Matt Matt 26th March 2017

    So is tan-zero-tan the normal “base alignment” for linebackers in the 4-3? What are the other possible alignments they can have?

    Working on coding a football game and want to incorporate all of the potential nuances involved

    • Joel Bishop Joel Bishop Post author | 6th April 2017

      Hi, this is a popular alignment for teams playing over fronts. Alignments are mostly based around their gap responsibilities. If you look at the 4-3 under front, the SAM linebacker is on the outside of the tight end. His responsibility is the D gap.

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