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Offseason Knowledge Base: Alabama’s base two-gap 3-4 defensive line

This is where football games are won and lost.

Texas A&M v Alabama Photo by Kevin C. Cox/Getty Images

Last week, I asked what kind of offseason coverage you wanted. Many of our readers, having never played the game wanted to know what the different positions are and what they do. That seems as good a place as any.

For our primer today, we start with the “base” Alabama defense, the 3-4. We say, “base,” but the scheme Alabama runs is a multi-look front that plays out of the nickel or dime just as much as it does the base 3-4. The Tide have even incorporated quite a few 4-3 and 3-3-5 looks the past few years as its type of recruits have changed and those players have brought new talents to the program to nullify the proliferation of spread offenses. In fact, as we continue this offseason, you’ll see that some of the most successful teams in college are countering the spread using a 4-3 Over Quarters base alignment.

But, we’re getting ahead of ourselves.

Anyway, this is the vanilla shell upon which all of Nick Saban’s defenses revolve: The 2-gap 3-4 scheme. Saban learned it from Bill Belichick, who had learned it from Bill Parcells, who had learned a variation of it from Bum Phillips, who had adopted it from college, particularly fom the OU Sooners juggernauts of the 40s and 50s.

When it became a mainstay of the NFL, it was a devastating equalizer to stop powerful down hill runners and still be flexible against the pass using oversized-but-athletic linebackers. Jim Mora, Don Shula, Belichick, Carroll, Parcells and many others employed the 3-4 look to great success well into the 90s. The Hoodie in turn passed along his accumulated knowledge of the defense to Pete Carroll and Nick Saban. They in turn passed it along to Nick Holt, Kirby Smart, Jeremy Pruitt, Mark Dantonio and so on.

Why does Alabama use the 3-4 as its base defense? The head man’s philosophy is an open book: Alabama has never disguised its intentions with respect to overall goals or playcalling strategy:

[Our] philosophy on first and second down is to stop the run and play good zone pass defense. We will occasionally play man-to-man and blitz in this situation. On third down, we will primarily play man-to-man and mix-in some zone and blitzes. We will rush four or more players versus the pass about ninety-percent of the time.

In all situations, we will defend the inside or middle of the field first – defend inside to outside. Against the run, we will not allow the ball to be run inside. We want to force the ball outside. Against the pass, we will not allow the ball to be thrown deep down the middle or inside. We want to force the ball to be thrown short and/or outside.

Thus, it all starts with stopping the run. And stopping the run begins with winning the battle up front, on the defensive line.

Without further ado, in its purest form, the 3-4 looks like this:

Base 3-4 defense

I’ll go ahead and plug in players from Alabama’s 2015-2016 rosters to make these positions make a little more sense, and we’ll say a little bit about terminology.

The Defensive Line and Responsibilities.

1. Along the front you have two defensive ends and a defensive tackle. In 2015, for instance, the Tide defensive front (left to right) looked this: Jonathan Allen (Strongside DE) A’Shawn Robinson (DT) and Jarran Reed (Offensive DE.)

The 3-4 front maximizes a player’s size and the ability to occupy space or take on offensive linemen. Especially at Alabama, these are heavier linemen than you see in a 4-3 defense; and, a good bit of that has to do with Alabama’s two-gap system.

With the defensive line occupying the OL, that frees up inside linebackers to run to the ball and make plays, while the outside linebackers can either act as a stand-up defensive lineman and pressure the quarterback or drop back into coverage depending on the defensive play call.

2. Each of the end positions requires a different kind of player in the 3-4, mainly as they relate to the quarterback. The majority of quarterbacks are right-handed, thus a strongside defensive end sees more pulling linemen, more lead blockers, backs in protection, and tight ends in pass protection. This requires that a strong side defensive end have superior upper body strength to shed the blocks from the best offensive linemen, and to very often beat or occupy double teams. Jonathan Allen was a strongside defensive end.

The weakside defensive end is usually the superior pass rusher. On the weakside, you emphasize superior speed, pass rushing ability, and footwork. The weakside defensive end is also usually responsible for neutralizing the right tackle, freeing up the outside linebackers to make plays. Jarran Reed did a great job of this, allowing Ryan Anderson and Tim Williams to terrorize the quarterback from the right side of the formation.

3. The defensive tackle (sometimes called the nose tackle) literally lines up nose-to-nose with the center. In many 3-4 schemes, the DT is just responsible for one gap on either side of the center. However, as we explain below, the defensive tackle in Alabama’s base 3-4 is still responsible for the gap on either side of the center. You want your bulkiest and strongest player at this position, but someone also with quick recognition and good footwork. The DT very often sees double teams and lead blockers, meaning that he occupies more than one blocker which in turn frees up the linebackers to make a play in the running game.

4. Pass-rushing skills are a bonus for a one-gap DT playing the nose. However, a two-gap 3-4 DT very often can pressure the quarterback. Alabama has been very fortunate in recruiting and developing Daron Payne. He can two-gap and make solo run stops, occupy more than one blocker, he has a good first step to split the center-guard to pressure the quarterback. He has worked on developing pass rushing skills, and they are finally starting show. It goes without saying, and as has been reported on several occasions, he is easily the strongest player on the team.

Let’s see how this works in practice (note, that Alabama has moved a lot of its players around on this play between the end positions and the nose; this is a ‘tweener lineup, so to speak. That versatility is hard to scheme against.)

This clip should have defaulted to the :20 mark; if not, forward the clip to that moment.

Here, you see Alabama in its base 3-4 defense. Once the ball is snapped, the strongside defensive end (here, A’Shawn Robinson) reads the play and moves down on his inside gap. He sheds the block of the left tackle and smashes the pulling guard into the backfield. The defensive tackle (here, Jarran Reed) takes on the center. He slips, momentarily, but in conjunction with A’Shawn’s play, has created a mess on the interior. Jonathan Allen is playing strongside defensive end (the side with the tight end.) He stands his man up, freeing the outside linebacker to make a play to the interior, slipping the block of the tight end. The middle linebackers and weakside defensive end recognize the play, and see that the offensive line is stoned at the point of attack. They crash down on the interior and backside to attack any remaining gaps or cutback lanes. The entire play is gummed up at the point of the attack by the defensive line, and Jarran Reed is then able to make the tackle and create a negative play.

The Alabama defense begins by stopping the run, and stopping the run begins with the defensive line.

One-Gap versus Two-Gap coverage

Pats base 3-4

Above we talk about gap responsibility and one-versus-two gap The easiest way to describe one vs. two-gap coverage is to actually see a photo of it. Above, you can see the Patriots in their base 3-4 coverage. The outside linebackers are playing off the line as essentially stand-up defensive ends.

As you look to the down linemen, you’ll see that that each player is responsible for occupying an offensive lineman while covering two running lanes. In a one-gap system, each defensive lineman is just responsible for one lane, while the linebackers behind them are responsible for the other lanes.

Alabama is a two-gap defensive front. This requires exceptionally powerful defensive lineman who have the ability to read the play in the backfield, step into the proper gap, and either make the play against the running game or neutralize an offensive lineman so that the linebackers can then clean up the play.


Closely related to “gap” is technique, often referred to as technique. This was a wholly arbitrary numbering system apocryphally credited to Paul Bryant that describes nothing more than where a lineman is aligned to carry out his assignment. The alignment is numbered 0-9, and the gaps that they are responsible for labeled A-B-C.

gap tech

Here is a gap / technique chart to put some sort of imagery with the jargon. And, it makes more even sense when you think back to Alabama players. We’ll use Jonathan Allen, whose exploits were highlight-worthy and probably still fresh in your mind.

For instance, Jonathan Allen’s NFL scouting report said that he is comfortable playing the 5-tech as a 3-4 end. He can also play the 3 and 1 tech as a 4-3 defensive tackle (the 1-tech here is called and labeled here 2i — all it means is “inside.”) At the combine, scouts observed that he was also working on learning the 9-tech (a 4-3 weakside defensive end playing outside the tackle) and the 6-tech (a 4-3 strongside defensive end lined up over the tight end.)

See? It’s not rocket science, but it does require learning some new vocabulary.

We can’t go as in-depth as we’d like to with these knowledge base articles, obviously. But, we hope to get your feet wet and take a lot of the tribalism and sophistication out of the equation.

Up next, we’ll tackle the linebackers; probably the most important personnel group on the field in a Nick Saban defense.