4-3 Defense Explained (Fronts & Coverage Guide)

By Steve

The 4-3 defense is common among professional and even youth programs. It’s easy to install and allows teams to use different personnel at different positions.

The 4-3 defense requires four defensive linemen and three linebackers. The three linebackers are often called Sam, Mike, and Will.

This article will learn more about the 4-3 defenses and the different varieties of defensive sets.

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The 4-3 Defense

While defenses in the NFL run various schemes, the 4-3 defense is a staple in every playbook. A 4-3 defensive look, by nature, consists of 4 defensive linemen and three 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.

4-3 Base Defense

4-3 defense in football

The base 4-3 look has no shading or shifting personnel to one side of the field. The interior DT is lined up over the Guards, the DEs are outside the Tackles with Outside backers lined up over the Tackles, and the Mike backer is lined up on the Center.

We saw how the 4-3 was altered to provide different looks as the game evolved.

4-3 Over Defense

4-3 defense in football

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 is split wide. The linebackers have gap assignments that perfectly fit with the defensive line.

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.

4-3 Under Defense

4-3 defense in football

The “Under” alignment is most notably different in how 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 have C-Gap responsibilities while Strong-Side DT is in the A-gap and the Weak-Side DT is in the B gap.

4-3 Linebacker Structure

The “Sam” linebacker is normally lined up across the tight end. A fair share of blitzing is 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 generally plays on the weak side and has more freedom than the other LBs. Of the three backers, the Will is most likely blitzing and is normally responsible for guarding against the screen. Generally, they also have heavier coverage responsibilities.

There are many Will linebackers in the NFL that are former safeties because of this.

The “Mike” linebacker is the linebacker in the middle. He has to be a downhill force stuffing the run up the middle while being versatile enough to drop into coverage for zone or man schemes.

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Coverages In The 4-3 Defense

Because most of the resources are dedicated to the run, a limited number of coverages can be run in a 4-3 defense. Having seven defenders in the “box” trying to stop the run means having four pass defenders playing coverage.

Man Coverage

The first and most simple is man coverage. Teams can play man coverage by matching the four defensive backs with the four receivers. Teams typically have one of the three linebackers’ play-man coverage on the running back out of the backfield.

This defensive coverage is most effective if the defensive back’s skills are greater than the wide receivers. If the wide receivers are talented, this may cause the defensive backs to, as they have no deep help.

Man coverage is also identified as cover 0 or cover 1.

Cover 2

Cover 2 is a common coverage played out of a 4-3 defense. It allows the three linebackers to be still dedicated to the run but still cover enough ground for the pass. The three areas covered are the hook/curl areas and the middle of the field.

Being the middle of the field in a cover 2, the weakness relies on the middle linebacker to drop into coverage to intercept crossing routes. Cover 2 isn’t perfect deep coverage; it does enough to disrupt low-crossing routes.

Learn more about cover 2 here.

Cover 4

Another popular coverage out of the 4-3 defense is cover 4. Teams can decide if they want to spot drop or man-match their cover 4.

We break down exactly what spot-dropping and man-matching are in the video below!

Teams can rotate to a one-high safety structure and play cover 1 and cover 3, but it’s a more advanced concept to teach younger players.

Installing The 4-3 Defense

Offenses can 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 four defensive linemen can 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 to 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.

Keep Learning

Learn more about defensive schemes below.

What Is The 3-4 Defense In Football?

4-2-5 Defense Football Coaching Guide

The 4-3 defense is often played against 21-personnel or 22-personnel offenses. To learn more about why personnel matters in football and how to play to your advantage, check out this blog here.

4-3 defenses are often played by coaches who face power offenses. Now that offenses have moved to a more traditional spread look, defenses are forced to match speed with speed. This often requires a linebacker off the field and running a 4-2-5 defense rather than a 4-3.

Do you run a 4-3 defense? Do you have questions about the 4-3 defense? In the comment section below, let us know how you run the 4-3 and what’s most effective for you.

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