A Guide to Identifying Defensive Fronts

[dt_divider style=”thick” /]What a time to be an NFL fan. The game is as flexible and multiple as ever and the lines have been blurred in regards to once extremely rigid concepts such as scheme, philosophy and the concept of players having defined positions.

Defensive fronts also fall into that category, as the once unique and scheme dependant alignments of defensive linemen have now become antiquated and Draconian, giving way to simpler, more conventional fronts. However, at the base of the simplicity are the rules put in place by the more structured fronts. That’s what we’re going to take a look at in this piece.

The common fan can tell you what a defensive lineman is, and probably be able to decipher if they play defensive tackle or defensive end. However, if you asked the casual viewer to expand on the difference between an Over and Under front, you’ll likely get a much less informative guess. We’re not going to get super into detail in this piece, but some basic identifiers to differentiate between the various fronts you can see on Sundays.

**Disclaimer – I was blessed enough with the opportunity to play collegiately at Carroll University in Waukesha, Wisconsin. These are the rules that I was taught as an offensive lineman to identify fronts. If you have other ways to diagnose the defensive fronts, that’s fine, but these are the ways that I know.

We’ll start with the most common and simple of the fronts:


This is an “Over” front. The easiest identifier is the 3 technique (outside shoulder of the guard) defensive tackle to the strong side. That’s not always the only identifier, but it’s a type of “All squares are rectangles, but not all rectangles are squares” type situation. An “Over” box is often a six man box, with the Sam linebacker or slot corner slightly displaced from the box the offense would count. The Over front is one of the most commonly used defensive fronts used in football due its ability to keep defenders in their specific gap. The backside defensive tackle can be in a 2i or 1 technique, whatever the preference of the defensive coordinator or player is, but they’ll have the backside A gap, and the 3 tech will have the strong side B gap. Those are the common staples of the Over front.


When I was a freshman at Carroll, I created a little method of deciphering between an Over and Under front in order to not embarrass myself in front of the upperclassmen in Offensive Line meetings. “Over 40, Under 50”. One way to tell if a defensive might be an Under front, is that it will look like a 50 (five man) defensive line because the Sam linebacker is up on the line of scrimmage.

However, the real for sure way to tell if it’s an Under front, is that the 1 technique defensive tackle is to the strong side. Under is the only front where a 1 technique will be to the strong side of the formation. This front has been made commonplace in the NFL by the Seahawks, Jaguars, Raiders, 49ers and Falcons among others. It creates more 1 on 1s with defenders and blockers than most fronts, and that puts more stress on the other offensive linemen to get to the linebackers, otherwise the linebackers have clear paths to make plays. Remember, if there is a 1 technique defensive tackle to the strong side (tight end side, usually) of the formation, it’s an Under.


The ‘Pro’ defensive front isn’t a very common front, only one school (St. Norbert’s College) that I played against in college ran it. It puts a lot of stress on the offensive line, as there is a defender for every gap.

In an Over front, the Sam linebacker is typically out of the “box”, but in a Pro front, there are 7 players in the box, which causes a lot of problems for the offensive line’s angles in the run game. This is the reference I made earlier to “All squares are rectangles, but not all rectangles are squares.” All Pro fronts are Over fronts, but not all Over fronts are Pro fronts.

The biggest way to differentiate from an Over and a Pro, is the Middle Linebacker. In a Pro defensive front, the “Mike” is in a 00 technique (head up on the center, second level defenders are given a second number to differ from the defensive line). This gives the offensive line very little leverage for either running inside or outside. This isn’t a common front, however, because it puts a ton of stress on your defensive ends, as well as your defensive backs. Having so many men dedicated to the box makes teams vulnerable on the outside.


The reason I put these three together is that they are all, at their base, three man defensive fronts with largely the same defensive line alignment. The main difference is how the linebackers are aligned around the defensive line.

The “Okie” front can be pretty easily identified as a 3-4 base defense. At Carroll, we called every three man front that wasn’t a Stack an Okie, although that didn’t necessarily mean it was a 3-4. The odd fronts used in today’s NFL are largely modified to Over/Under rules up front in order to be flexible enough to switch from one to the other if need be.

The main thing to see if a front is a true “Okie” front is the 0 technique (head up) nose tackle, and the two 5 technique (outside shoulder of the offensive tackle) defensive ends.


You’re probably saying, “Owen, this is, like, the same damn thing.” And you’re not far off. The biggest difference between an Eagle front and an “Okie” front is that all three defensive linemen are inside of the five offensive linemen, and the outside linebackers are head up on the tight ends.

The biggest thing this does is create a ton of congestion and “trash”, making the running back’s read difficult. This allows the two inside linebackers to sort through the “trash” and find the running back. This is a common defensive front of the Wisconsin Badgers with Jim Leonhard as the defensive coordinator.

As you can see, there isn’t a ton of difference aesthetically from the Okie front, so you can imagine why for the sake of quick recognition, they’re called the same label, although there are slight differences.


The Stack is called a few different names: Stack, 3-3-5, 3-5-3. Whatever you want to call it, it’s a three man front, called “Stack” because the linebackers are “stacked” directly behind the defensive linemen. This causes confusion for the offensive line, as the defenders aren’t in declared gaps at the snap of the ball.

This defense was primarily developed to stop spread offenses, and the 3 man defensive line makes it similar to the Okie and Eagle fronts. The other main calling card of this defense are the hybrid linebacker/safety positions. They’re called a lot of different names, usually dependent on the mascot of the team employing the scheme, and they’re coverage players who are also dangerous blitzers.


The “Bear” front is essentially what teams run on the goalline, when offenses condense and try to cram the ball into the end zone by overpowering the defense. The main calling card of the Bear front is that the interior the offensive linemen (Guard, Center, Guard) are covered up by the defensive line. They can be head up, or shaded, but if the inside three are covered, it’s a Bear front.

This creates almost exclusively 1 on 1 blocks up front. The more of those situations a defense can create, the tougher it is for the offense to execute. However, on the flip side, the offense can break a big play if the defensive line doesn’t win. With so much dedicated to the line of the scrimmage, if a running back can break through the line, there’s little resistance waiting for him.

Follow Owen on Twitter @RieseDraft. Read the Big Ugly Spotlight Game Review of Alabama vs Florida State here, the review of Oklahoma vs Ohio State here and the review of USC vs Texas here.

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