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The 4-3 Under Defense, Part II: The Seahawks' Hybrid

A look at the 4-3 Under defense that the Seahawks ran in 2010. How it works, what type of personnel it needs, and where it will be going in 2011.

The main thing that Pete Carroll preached at USC was 'gap control'. In his tenure there they usually stuck with a pure 1-gapping system to keep it simple and to dictate clearly each player's responsibility. As he put it, "In principle we want to give our players a chance to know exactly what they have to defend. We also want to give them an attitude in which to do that. We want to be an attacking, aggressive football team. We don't want to sit and read the play like you often have to with "two-gap" principles of play. We want to attack into the gap at the snap, get off the ball to play on their side of the field and get after the quarterback.

The big problem with any "one-gap" approach however is that it allows a ball carrier to get into the secondary if one guy makes a mistake. No matter how aggressive the defense is there is a great amount of discipline that goes with this defense. You have to be very strict about your positioning and the placement of your players. You have to have the ability to maintain relative spacing between your players.

But, he also noted, "I run (my 4-3 defense) with one gap principles but can also make it work with some two gap principles."

The current Seahawk gap responsibilities are not as fixed per se. At USC it was mostly a one-gap system, but in the NFL and here in 2010 you saw Red Bryant 2-gapping at the 5-tech spot, and Colin Cole as well at the strongside D-tackle 1-tech spot.

This type of thing is pretty dependent on the type of players you have available to you and whether or not they're effective at two-gapping. Bryant is a good to potentially great two-gapping defensive end. He was able to control two gaps in his location which took a lot of pressure off the MIKE linebacker and strong side safety in run support. With two-gapping 1-tech you just hope to plug up a lot of room in the middle of the line and draw double teams from the center and guard; the 1-tech will not be responsible for rushing the passer. The 3-tech in the Seahawks' defense will typically be faced with a lot of one-on-one matchups due to the alignments and will only be responsible for the B gap- and ideally be able to pressure the quarterback through his gap on every passing down.

Dan Quinn, the D-Line coach in 2010, and Pete Carroll, both came up in their coaching careers under Bill McPherson in San Francisco, who instilled in them 2-gapping principles in a 1-gap 4-3 system, and his principles were among those that the Hawks implemented in 2010. As Clare Farnsworth noted in Week 6 last season, after the Hawks had demonstrated a very solid run defense through 5 games:

"The secret to the Seahawks' success in holding their first five opponents to an average of 70.4 rushing yards - and 2.9 per carry, also second-best in the league - actually has a back history. As in way back, to when coach Pete Carroll and defensive line coach Dan Quinn were with the San Francisco 49ers.

Carroll was the 49ers' defensive coordinator in 1995-96, while Quinn was the D-line coach in 2003-04. But the common bond that connected their tenures was Bill McPherson, now retired after serving in a number of capacities during an influential 20-year career with the 49ers. The tricks Carroll and Quinn learned from McPherson are producing the treats the Seahawks' run defense has been producing on a weekly basis."

In that article, Pete Carroll explains McPherson's influence in a little more detail:

"We made some scheme adjustments to the style that was here in years past, and really the style that I've been playing in college, and I flipped it all the way back to when I was at San Francisco. It was the last time we've played this formula of defense.

"Danny Quinn has had a big role in that because of his crossover to the days when he was at San Francisco. We were both affected by a guy there - Bill McPherson, a coach that was there for us. And Mac taught us some stuff. Now we brought the expertise to at least be able to explore it."

The exploration Carroll mentions refers to their hunt for a LEO (Chris Clemons) and an effective 5-tech (Red Bryant) but also refers to their evolution to a two-gapping 4-3 Under - a defense that has a lot of similarities to a 3-4. This is something that Carroll avoided mostly at USC but has now put in place with the Seahawks and is something he picked up from his days in San Francisco. We saw it achieve a level of success through the first month or two last season but then injuries in key positions began to pile up.

When Red Bryant and Colin Cole went down in 2010, Pete tried to stick with the 2-gap principles he had been using with this starting players. Unfortunately the replacement players in Kentwan Balmer, Junior Siavii, and a few others weren't as effective in that system. Later in the season the Hawks switched to a more traditional 1-gap 4-3 system with Raheem Brock manning the strongside defensive end position where Red Bryant started the year. Brock was more effective there with a one-gap responsibility and the Hawks had a little better time with it.

As with any defense, the 4-3 Under is able to evolve and change based on personnel so it's a bit hard to guess how it will look in 2011. Dan Quinn, who helped Pete institute the 4-3 Under 2-gapping hybrid, has now left to coach in the college ranks and the Hawks new defensive line coach is Todd Wash, who comes to Seattle via Tampa Bay - where the Bucs ran mostly a 4-3 Tampa-2 defense that uses almost entirely one-gap assignments.

So really, I don't know what to expect in 2011.

Time will tell, but there are two things I know: One, Pete Carroll is not going to give up on this system. He said, "I have been running that same base defense since 1977 when I learned it from (Monte Kiffin). I have used variations of this defense my entire career. I have stayed with its principles through all my years of coaching. I have a real strong belief in this defense. I know the defense and its adjustments so well that my belief system in it is strong and rock solid." So if you're hoping they abandon this defense you're probably going to be disappointed.

Two, it will not work efficiently with the manpower we had last season. We have seen the beginning of the rebuild and they are bringing in the guys that will fulfill Carroll's specific needs.

The other thing that might make people nervous about this defense: It is geared to stop the run. That is it's main purpose. It stops the run and hopes to use pressure on the quarterback to diminish the passing attack.

So our defense is designed with the number one goal of stopping the run in a pass-happy league. Great, right? Well, alone that makes me kind of nervous but it's also why you see the Seahawks developing their Nickel and Bandit players. Speedy, ballhawking secondary players to use in passing situations. Kam Chancellor and Malcolm Smith replace regular linebackers in Bandit to play in pass defense but are good enough to stop the run. Mark LeGree is a big hitter in run defense but can also play the deep middle to protect against over the top throws. To an unknown extent, Brandon Browner and Byron Maxwell are theoretically big hitting cornerbacks that can still defend the pass. This vision is starting to come together it seems.

Carroll is not necessarily stubbornly sticking with a 'dying' defense predicated on stopping the run in a league where passing wins. His defense is evolving - it is designed to stop the run but pressure the passer and can morph into a scheme that is excellent in pass coverage as well. Theoretically.

Here's the key though: while the Hawks run defense was pretty admirable in the beginning of the year their pass defense was still pretty atrocious because of one main reason: They could not get interior pressure on the quarterback. Sure, some fault lies with the corners and safeties in their coverage but even the best defensive backs have trouble if the quarterback has all day to pick their target. And, sure, Clemons and Brock combined for 20 sacks but their 'premiere interior pass rusher" (in Pete's own words), i.e., their 3-tech, amounted for only one sack. In this version of the 4-3 Under, the 3-technique does not have to wait and see if it's a run or a pass and play off of a read. When the ball is snapped he smashes, dashes, spins and violently makes his way towards the football and destroys anything in his path. In years past in the 4-3 Under defense, you look and can find 3-tech defensive tackles amassing double digit sack numbers. Though Brandon Mebane did get a fair amount of QB hurries this season, in this system where the 1-tech and 5-tech basically sit back and try to stop the run, it would seem to me that a QB has a better chance of escaping a hurry and completing a pass. We need sacks and we need to force the QB to make quick, poor decisions. In a league where the 3-step drop appears prominently, pressure from the edge comes far too late to make an effect.

In a nutshell, unless the 3-tech defensive tackle can, in conjuction with the LEO and a blitz now and then, get more pressure and sacks on the quarterback with some consistency, the opposing teams will pass the crap out of the ball and pick apart our defense. That happened a lot in 2010 and was a major reason the Hawks were at the bottom of the NFL in pass defense. How that 3-tech position will be addressed remains to be seen.

It is to the eternal consternation of fans that the Hawks didn't draft a 3-tech defensive tackle this season or last. Until we have a decent to great player in that spot, things will be tough. Brandon Mebane's future is up in the air and the Hawks haven't shown a marked fervor in getting a deal done. I can only assume one of two things: that they're either posturing and still want to re-sign him, or they just don't see him as effective at that spot and are willing to let him walk. If he does walk, someone will have to be signed in free agency because the depth is basically ...nobody. Something tells me though that they've got some sort of plan up their sleeves and I'm hoping to see that unfold soon.

Like last season, I can expect that they'll bring in a multitude of players to compete at the spot and hopefully find a diamond in the rough there. We'll see.

In my next couple of posts I'll delve into each position and get more specific about what Carroll looks for. I'll talk a bit about some of the zone coverage schemes we use. I'll talk a little more about the history of it all. It should be fun.