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Understanding the 4-3 Defense Under Robert Saleh

June 24, 2017

The 49ers are opening the “new era” with an unfamiliar scene. A player, turned media analyst, turned GM, a exciting new head coach that brings a plethora of knowledge on offense, and a defensive coordinator running a rather familiar defense that the 49ers have battled against for the past few years. This isn’t a story about Kyle Shanahan, but rather a story about Robert Saleh, the defensive coordinator, and the defense that he will be trotting out on Sundays this upcoming season.

 

So, what is the 4-3 defense? 

 

The 4-3 is four down lineman (two defensive ends and two defensive tackles) and three linebackers. First, its all about the gaps. The offensive line have four different gaps: The A gap (between the center and the guard), the B gap (between the guard and the tackle), the C gap (both sides of the offensive tackle), and the D gap (the outside shoulder of the tight end). So gap alignment is important. In technical terms, there are nine different technique positions, these positions determine where you play on the defensive line to attack the various gaps. Even numbers indicate playing on top of a offensive lineman, in example, zero technique plays over the top of the center and four technique plays over the top of the offensive tackle. In a 3-4, the defensive lineman would play over the top of offensive lineman since they have to be responsible for two different gaps. Traditionally in a 4-3, however, the defensive lineman play one gap, meaning they would play the odd techniques, like one (A gap), three (B gap), and five which can occasionally be seven if a TE is on the field (C/D gap).

 

Now, there are three variations of the 4-3 defense, the 4-3 over, the 4-3 under and the bear. The 4-3 over indicates that the defense is shifted to the strong side of the offense. In this set, the over tackle, also known as the three technique, plays the B gap on the strong side, the nose tackle, or one technique, plays the A gap on the weak side of the defense. As for the defensive ends, the big end, or the five technique plays on the weak side where as the other defensive end typically plays on the outside shoulder of whoever is on the strong side of the defense (typically the tight end, which means he would be the seven technique. The concept of this variation of the 4-3 is to make it hard for the offensive line to double team a defensive lineman without another lineman coming free.

 

The 4-3 under flips the defense, traditionally this is the ideal defense to rush the quarterback. The weak side defensive tackle plays the 3-tech, or the B gap, the weak side end then plays the 7-tech or even possibly the 9-tech so that he can just go after the quarterback, and the strong side linebacker plays on the outside shoulder of the tight end. From this formation, it puts pressure on the linebacker playing over the weak side end to stop the run. The 4-3 under comes from the Tampa-2, a defense alignment implemented by Monte Kiffin which became popular during his days with the Tampa Bay Buccaneers (more on this later).

 

The Bear defense (which some call the Double Eagle) is kind of line the 46 defense that was made popular by the 1985 Chicago Bears. In this defense, your nose tackle aligns up over the center (0-tech), your defensive tackle playing the B gap (3-tech), your big end playing inside at the B gap (3-tech) and your other defensive end playing outside at the five or seven technique. It also shifts your strong side linebacker to the five or seven technique and creates a 5-2 look for your defense. It also has your safeties drop closer to the line of scrimmage. This formation is not what you want to use in pass situations, only in run situations. It puts your cornerbacks at a disadvantage.

 

So, what is unique about Saleh’s defense?

 

Saleh’s defense stems from Pete Carroll’s coaching tree. Gus Bradley and Dan Quinn are also using this defense today. To go into why it is unique, we have to go back into Pete Carroll’s past. After Pete Carroll graduated from Pacific college, he got into coaching as a graduate assistant. He spent three years there until he moved to Arkansas in 1977. At this time, a man named Monte Kiffin had just signed on to be Arkansas’ defensive coordinator. Carroll was only 25 years old at the time however, Monte Kiffin knew he had potential. In an interview with ESPN, Monte Kiffin said,

 

“A month later [after hiring him], [Arkansas head coach, Lou Holtz] said, ‘Who is that young guy in the back of the room?' I said, ‘Well that there is Pete Carroll, coach. We hired him a month or so ago. Get to know him because he won’t be here long.” (via ESPN.com)

 

Kiffin was right, Carroll went from being the graduate assistant at Arkansas to being the secondary coach at Iowa State. As stated before, the 4-3 under formation stems from the Tampa-2 defense that really came into being with Monte Kiffin. Safe to say, Pete had a great mentor. In the same ESPN article, Pete states,

 

“I owe him everything… He taught me everything I know about defense.”

 

So what makes Pete Carroll’s defense unique is that he values speed, instincts and athleticism over size.

 

What is the LEO?

 

This also goes back to not only Monte Kiffin, but also former 49ers head coach, George Seifert. In the 4-3 under scheme, George Seifert wanted to put the offensive line at a disadvantage on passing situations putting the weak side defensive end on the outside edge standing up (or in the two point stance). George Seifert called this position the Elephant, which Pete Carroll now calls the LEO. Typically your LEO is the most athletic defensive lineman. He needs to be able to just fly at the quarterback, however he also needs to be twitchy enough to react quickly to control his gap assignment in case of a run. 

 

So, with so much emphasis on pass rushing, how does this help the run defense?

 

The weak side linebacker is going to be involved in a lot of action, typically he is helping with the C gap and the weak side linebacker (or the WILL) needs to be one of the best tacklers on the field. The strong safety plays closer to the line of scrimmage and the cornerbacks need to be long and physical because the will be relied on to come up on run support. The one-gap system makes it easier on the defensive lineman to just attack their gap responsibility rather than read and react (one of the biggest issues in Jim O’Neil’s defense in 2016). 

 

What about the defensive backs?

 

The defensive backs typically run press man or cover three, or three-deep zone. The free safety is the main cover man, or the center fielder of the defense. He is the main player that covers the middle of the field, or reading and reacting to throws. The cornerbacks are the boundary cornerbacks, and as stated before are longer and more physical than the average cornerback. They need to be quick, but mostly need to be able to come up in run support. The strong safety is responsible for playing near the line of scrimmage, covering the flat or playing man to man with the tight end. 

 

While we sit and wait to see who officially lines up where on the defense, one of the most important things to make this defense successful is finding the right players. We won’t know if the 49ers will be successful running it, however, Kyle Shanahan worked with Dan Quinn in Atlanta last year and Robert Saleh worked with Pete Carroll and Dan Quinn in Seattle. Not only that, but John Lynch played in Monte Kiffin’s defense the year they won the Super Bowl in Tampa. So whatever happens, it should be fun to watch.

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