The Different Looks of the 4-3 Defense
While defenses in the NFL run a variety of schemes, the 4-3 defense is a staple in essentially every playbook. A 4-3 defensive look, by nature, consists of 4 defensive lineman and 3 linebackers. Within this 4-3 personnel grouping, there are multiple different looks a defense can use to stop an offense.
Regardless of the alignment, the 4-3 defensive front, this scheme is all about gap control. Each player has the responsibility of one gap. With that in mind, let’s look at a few different alignments we are likely to come across in a game.
The base 4-3 look has no shading or shifting of personnel to one side of the field. The interior DT are lined up over the Guards, the DE’s are outside of the Tackles with Outside backers lined up over the Tackles and the Mike backer lined up on the Center. As the game evolved, we saw how the 4-3 was altered to provide different looks.
As depicted above, the “Over” alignment calls for a slightly different look than the base call. We have a DT lined up in the “Open” or Weak-Side A-gap, with the other DT lined up in the B gap of the opposite side. The DE on the “Closed” or Strong-Side is head up on the Tight End while the Open side DE is split wide. The Linebacking corp is noted above as being lined up to have gap assignments that fit perfectly with what the defensive line could not match up with. Lastly, note that “Tan-Zero-Tan” as written above the linebackers refers to Tan meaning to shade the Tackles and Zero to being over the Center.
The “Under” alignment is most notably different in the way the linebackers are dispersed. The ‘Sam’ backer is left most backer in the picture above with responsibilities of the D gap, the ‘Mike’ backer is now on the Closed side B-Gap, and the ‘Will’ Backer is on the Open-side A gap. The defensive ends both have C-Gap responsibilities while Strong-Side DT is in the A-gap and the Weak-Side DT is in the B gap.
Overview of Linebackers
The “Sam” linebacker, is normally lined up on the across from the tight end. There is a fair share of blitzing that can be done from this position, but this backer is big in stopping the run. Because of this, they are usually a bigger linebacker than the “Will” backer. Finally, he will usually be relied upon to cover the tight end or potentially a back out of the backfield.
The “Will” linebacker, will generally play on the weak side and typically has more freedom than the other LBs. Of the 3 backers, the Will is most likely to be blitzing and is normally responsible for guarding against the screen. Generally, they also have heavier coverage responsibilities. There is a good number of Will linebackers in the NFL that are former safeties because of this.
The “Mike” linebacker, if of course the linebacker in the middle. He has to be a downhill force stuffing the run up the middle while being versatile enough to also drop into coverage for zone or man schemes.
What’s the Point?
Offenses have the ability to run anything from the spread offense to a power run (I-formation) attack. Having a base defense that is versatile enough to produce different looks is crucially important for a defense. The 4-3 Under is almost a 5-2 front that puts the defense in a position to dominate the line of scrimmage.
The 4-3 is most effective when the 4 defensive lineman can not only protect their gap against the run, but get after the passer. This defense is designed to stop the run with the gap assignments but can be exposed when there is no pressure on a passing attack. At high levels of football, the 4-3 is just a piece of what a defense does and should be mixed in with other looks.
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