4-3 Defense Explained (Fronts & Coverage Guide)

Written By: Chris Haddad
Updated: February 12, 2024

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.

The 4-3 Defense

While defenses in the NFL run various schemes, the 4-3 defense is a staple in every playbook. This 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, 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 Defensive Lineman Structure

4-3 defense in football

The base 4-3 look has no shading or shifting personnel to one side of the field. The interior defensive tackles are lined up over the offensive guards, the defensive ends are outside the offensive tackles, with the outside linebackers lined up over the offensive tackles, and the Mike linebacker is lined up on the Center.

The point of the nose and tackle was to play through the offensive guards and try to aggressively make a tackle. If they get a double team from the offensive line, they need to fight through it to not get pushed back into the linebackers.

The defensive ends are responsible for containing any run to the outside. This means they need to force it back to the inside.

In order to get your defensive ends lined up properly, many coaches will use a numbering system to tell players of their positioning.

defensive line techniques

Here is a cheat sheet you can use, to help your players. Learn more about defensive techniques and alignments here.

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 defensive tackle lined up in the weakside A gap, with the other DT lined up in the B gap of the opposite side.

The defensive end on the strong side is on the outside shoulder of the tackle, or you can move him to head up the tight end.

The linebackers have gap assignments that perfectly fit with the defensive line. This is called single gap responsibilities, as everyone is assigned one gap to maintain.

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 linebacker is the right linebacker in the picture above with responsibilities of the D gap, the ‘Mike’ backer is now on the strong side B Gap, and the Will Backer is on the open-side A gap.

The defensive ends have C-Gap responsibilities while the strong side defensive tackle is in the A-gap and the weak side defensive tackle is in the B gap.

The major change between the over front and the under front is where the nose and tackle line up. Notice the tackle (3 technique) is lined up away from the tight end.

This allows you to slide your linebackers to that side, as the weak side is closed off by the 3 technique and 5 technique defensive end.

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 (also known as the weak side linebacker) generally plays on the weak side and has more freedom than the other LBs. Of the three backers, Will is most likely blitzing and is normally responsible for guarding against the screen, reverses, or any weak side runs. 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.

Out of all of the linebackers on the field, the Mike linebacker should be the most talented, smartest, and willing to make contact with other players.

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

4-3 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

4-3 cover 2 defense

Cover 2 is a common zone coverage played out of a 4-3 defense. It allows the three linebackers to be still dedicated to the run but still covers 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.

This is a common defense at all levels of play, including youth football.

Learn more about cover 2 here.

Cover 4

4-3 Cover 4 defense

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.

This zone defense is crucial on 3rd and long passing downs.

If you want to play match coverage on first and second downs, this is also an option.

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 in run support but also create pressure through a base rush.

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 fronts and multiple coverages.

If you’re looking to install the 4-3 defense, we recommend checking out this course which can help you get started from a fundamental level.

Keep Learning

Defensive coordinators may choose different schemes that involve two deep safeties or 3 linebackers. But the key is to look at how many defensive linemen are on the field. This will help you to dictate what package the defense is in and what the philosophy of the head coach is.

The key to a dominant defense is having a good nose tackle, disciplined defensive ends, linebackers who can track both run and pass plays, and fast/aggressive defensive backs (strong safety and free safety).

If you want to improve your defensive play, we recommend checking out our position courses, which will have your entire defense technically sound.

If you want to learn more about defensive schemes, read these articles below.

What Is The 3-4 Defense In Football?

4-2-5 Defense Football Coaching Guide

This 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.

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.

About the author 

Chris Haddad

Chris Haddad is the founder of vIQtory Sports & high school coach for over 12+ years. He has been featured as an authority on Hudl, Bleacher Report and countless other football-centric platforms. Chris continues to study and provide valuable content for those looking to learn more about the game of football.

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