The 3-4 Defense: The Complete Guide

Posted by John Grayson on

The 3-4 Defense has stretched across pro and college football.

Between two coaches running the 3-4, 9 College football national championships have been won using a version of this defense since 2005. In the NFL, 7 Super Bowls have been won in that time frame from the same coaching tree.

That's 16 major championships from 3 coaches, all coming from the same 3-4 coaching tree. Belichick, Saban, and Smart all use a version of the 3-4 to do their business, and business has been good! 

So what exactly is the 3-4 defense, and how does it work?

Well, let's find out.

What is the 3-4 Defense?

The 3-4 defense is a defense with 3 down linemen, 4 linebackers, and 4 defensive backs.

3-4 Defense vs I Formation

The defense uses the two “outside linebackers” to create matchups that increase the difficulty on an offense. TThis even distribution of players makes the defense a “mirror” defense meaning one side mirrors the other in a base set. 

What Personnel is Needed to Run the 3-4 Defense?

The 3-4 defense employs bigger stronger defensive linemen that will necessitate a “two gap” approach to their play. This means they will have to control two gaps of the offense. Outside linebackers traditionally are a “hybrid” type, meaning that they can rush the passer, or drop into coverage.

3-4 Defense vs Ace Formation

The four linebackers have different names for each position depending on which playbook you're using, but one common way to refer to them is by the names "Sam", "Mike", "Will" and "Jack" like you see in the diagram above.

The secondary plays with two corners, and two safeties. The bigger linemen up front, along with traditionally bigger inside linebackers allows the defense to play with  two safety set up, which enables the defense to be secure against the run and the pass. 

What are the Strengths of the 3-4 Defense?

The biggest strength of the 3-4 defense is the ability to bring pressure from so many places because of the extra linebacker in the defensive alignment.

For example, in the 3-4 defense, you can “send” or “Blitz” both outside linebackers and create a 5 man rush. This can be helpful in rushing the passer (5 rushers vs. 5 linemen) and it can also be helpful against stopping the run. The two safety set up can also be very difficult for an offense to scheme against because you can do so many things with it.

The two safety set up lends itself to cover 2 or cover 4, but very easily, a defense can send an extra rusher, and replace him with one of those safeties. In a scenario like that, a defense could play cover 1 or cover 3 while sending that blitzer. This completely changes the picture for a quarterback as well as an offensive coordinator. 

Weaknesses of the 3-4 Defense

In many of today’s modern spread offenses, the 3-4 runs into issues in its traditional, base alignment.

3-4 Defense vs Spread Formation

Two receivers on both sides, necessitates the outside linebackers to get involved in coverage. When this happens, the 3-4 defense will only have a 5 man box. This is problematic, because the offense has 5 blockers, plus the back who is running the ball. Someone on teh defense has to beat their man, or the offense has the advantage. 

How Do Offenses Like to Attack the 3-4 Defense?

The more spread out the 3-4 defense becomes the easier it is to run the ball against it. A light 5 man box can become problematic, and leaves the 3-4 defense vulnerable. This has lead to the rise of the 3-3 stack defense, which removes 1 safety and adds another linebacker to defense against today's modern spread offenses. Any sort of trips formation can lead to confusion when it comes to the 3-4 defense. The defense will likely have to roll a safety down, or put a linebacker in coverage. Against the speedy slot wide receivers almost every team has, this can become problematic for the 3-4 defense. 

Common Blitzes from the 3-4 Defense

Weakside Edge Blitz

3-4 Defense Weakside Edge Blitz

Blitz 1 sends an outside linebacker off an edge. This combined with a Defensive line slanting away from the blitzer creates an over front from a 4 man front. The 4th rusher plays what a traditional 5 tech, defensive end would be. The 4th rusher is replaced in coverage by one of the high safeties.

This gives a 2 high pre snap look, but post snaps plays a 1 high cover 3. This blitz shows the versatility of the 3-4. Pre snap shows 3 rushers and 2 high safeties. Post snap there are 4 rushers and the defense is playing cover 3, which is a completely different picture.

"Crossfire" Blitz

The Crossfire Blitz sends both inside linebackers in a crossing pattern. Pre snap, the defense gives the appearance of 4 rushers, looking as if one of the outside linebackers will be rushing with the 3 defensive lineman.

3-4 Defense Crossfire Blitz

On the snap, the outside linebacker drops into coverage, and the two inside linebackers blitz the quarterback. This again shows the versatility of the 3-4 defense. Similar to blitz 1, the pre and post snap look are very different to the offense. Similar to blitz 1, the defensive secondary will start with 2 high safeties giving the offense the appearance they will be in a two high coverage (cover 2, cover 4, cover 2 man) but on the snap of the ball, one of the series will rob the seam and the defense will play cover 3.

Common Coverages from the 3-4 Defense

Cover 4

3-4 Defense Cover 4

Cover 4 is a common coverage from the 3-4 defense. This is a common coverage to stop the pass. This coverage has 4 deep defensive backs, and 4 linebackers in coverage underneath. This is a very easy coverage to play as it defends against the deep pass as well as the underneath passing game. Cover 4’s only vulnerability is the flat.

Cover 2 Man

3-4 Defense Cover 2 Man

Cover 2 man gives the same exact pre snap alignment as cover 4, but with very different responsibilities. Cover 2 man is a man to man defense with two safeties over the top providing help to the underneath man defenders.

In coverage #1, cover 4, the defense is vulnerable in the flats. This coverage will give a similar pre snap read to a quarterback causing him to make a flat throw, but with the defense in a man to man coverage, that flat throw is now defended.

What Coaches/Teams Use the 3-4 Defense?

Bill Parcells & Bill Belichick

When I hear the 3-4 defense I immediately think of the “Two Bills” also known as Bill Belichick and Bill Parcells who teamed up on the great New York Giants teams of the late 80’s and early 90’s.

Bill Parcells and Bill Belichick - 3-4 Defense

The two used the 3-4 defense, along with Hall of Fame linebacker Lawrence Taylor to win two Super Bowls. The “big blue wrecking crew” as it was known used big strong linebackers and defensive linemen to stifle teams and their offensive attack. 

Nick Saban & Kirby Smart

3-4 Defense - Nick Saban & Kirby Smart

From Parcells and Belichick and the “Big Blue Wrecking Crew” came the Belichick with a nod to Parcells coaching tree. From that tree you get Matt Patricia, who won 2 Super Bowls running a version of the 3-4 under Belichick. Before Patricia, Romeo Crennel was the Patriots defensive coordinator. He used his knowledge of the 3-4 to grab head coaching jobs in the NFL as well as stints as a defensive coordinator elsewhere. Crennel also won super bowls with the Patriots.

Maybe the most famous disciple is Nick Saban. Saban was the defensive coordinator under Belichick during Belichick’s first head coaching job with the Cleveland Browns. Saban took his knowledge of the 3-4 to LSU and Alabama where he has won 7 National Championships.

Sabans most famous disciple (who by osmosis is a 3-4 disciple of Belichick and Parcells) is Kirby Smart. Smart was Saban’s defensive coordinator at Alabama where he won the Broyles Award as the nation's top assistant coach. Smart won 4 National Championships as a defensive coordinator under Saban at Alabama, and has won back to back National Championships as the head coach at the University of Georgia.

Want more?

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