Everything You Need To Know About Dan Quinn's Defense

Under Rex Ryan, we have come to expect a dominant defense. With the potential hiring of Dan Quinn, a defensive coordinator, a number of fans are afraid that those days are gone and that Quinn is, in effect, a downgrade from Ryan. Although that of course remains to be seen, it's important to understand what Quinn brings to the table. After all, the Seattle Seahawks have had the number one overall defense in the league both years that Quinn was their defensive coordinator.

Under Ryan, the New York Jets ran a multiple defense. That means they ran a base 3-4, three linemen and four linebackers, but you could see a number of different formations, ranging from zero linemen to five or more. Cornerbacks were generally lined up in man coverage, with zone peppered in at times. The scheme was organized chaos, with the goal of confounding the opponent into submission.

The defense that Quinn runs as defensive coordinator for the Seahawks is, in many ways, the polar opposite. It is a base "4-3 Under" scheme, which I'll explain in more detail in a moment. It's an old scheme that has stood the test of time, and executed properly with sufficiently capable personnel, is very difficult to defeat. At its core, there are four defensive linemen, three linebackers, and the cornerbacks are mostly in a "Cover 3" zone. Although there can be some deception involved, this scheme mostly relies on fundamentals, execution, and simply overpowering your opponent. Although this scheme is less complicated than Ryan's scheme, that does not make it simpler.

It also doesn't mean Quinn is married to this scheme. He is known for adjusting his scheme to fit his players and putting players where they can succeed. The Seahawks also heavily use a 4-3 Over and Bear front, which I'll describe in future articles. So this may not be the final result we'll see if he comes to the Jets.

So, what is the 4-3 Under? How will the Jets fit into this scheme? I will attempt to boil this down to its simplest explanation, but please feel free to ask in the comments below if you have any questions.

As I mentioned, it involves four defensive linemen. One is positioned at the four technique ("tech"), one at the one tech, one at the three tech, and another at the LEO position. I'll explain the LEO a little more in a bit. It goes by other names as well, such as Elephant.

But first, a refresher in the where each of those spots line up, in case you forget:

So you can see, the four tech is just inside the right tackle, the one tech between the guard and center, and the three tech is on the opposite side of the four tech just outside the guard. Now is also a good time to say that it isn't always exactly as I just described. Sometimes they'll line up at slightly different techs, sometimes they'll have slightly different roles, sometimes they'll flip sides. But generally speaking, this is how the linemen line up in a 4-3 Under.

Of course, that's not the end of it with these guys. Each of these guys has certain jobs to do. The four tech has a two-gap responsibility, which means in the above description, he's responsible for the B and C gaps. Similarly, the one tech also has a two-gap responsibility, which means he's responsible for the A gaps. The three tech, on the other hand, just has one gap to worry about, the B gap. Their job is to get a yard upfield and to hold their spot, snuffing out running lanes. Here's an image to help you visualize this, courtesy of FieldGulls:

The strong side one tech must be able to take on a double team consistently. The weak side defensive tackle, the three tech, must be an interior pass rusher and have an explosive first step. His main job is to pressure the quarterback and stop the run in his weak side B gap. The four tech defensive end can be a bigger guy and must be great against the run.

With the team's current personnel, you would likely see Damon Harrison at the one tech, Sheldon Richardson at the three tech, and Wilkerson at the four tech. Harrison is a monstrous beast that can tie up the center and a guard. Richardson is developing into a great interior pass rusher, and Wilkerson is a force as a run stopper. The defensive line wouldn't need much retooling, as the Seahawks often use 3-4 personnel, which is what the Jets currently have, to run their 4-3.

Now, on to the LEO position. It's sort of a hybrid lineman/linebacker position whose job is mainly to rush the passer. Their hand can either be in the dirt or standing up, depending on what the player prefers. The LEO is always on the opposite side of the four tech defensive end, and generally on the weak side of the formation. In the image above, the left side is the strong side so you'll find the LEO on the opposite weak side. Their goal is to ruin the quarterback's life. In some ways, Jason Babin may be the best suited for this role. It isn't too different from the Wide-9 role he's succeeded in throughout his career.

The other player you might have seen in the image above is the SAM linebacker. He is lined up to the outside shoulder of the tight end off the line of scrimmage a yard or two and is responsible for the D gap, outside of the tight end. He's also sometimes responsible for running in pass coverage. The other two linebackers are the MIKE and the WILL. In the image above, that's #54 and #56. The MIKE is responsible for the strong side B gap and the WILL the weak side A gap.

To quote FieldGulls:

The SAM linebacker needs to be athletic and rangy; great against the run but able to run with tight ends and running backs in pass coverage. The WILL linebacker is going to get a lot of tackles and in Pete's system is typically a faster, smaller linebacker with range. The MIKE linebacker needs to be the field general; very instinctual and savvy. He needs to be quick enough to drop back down the middle third of the field in pass coverage in the Tampa-2 coverage.

Right now, I don't think the team has the personnel for the linebacking corps. Demario Davis would probably make a very good WILL, but otherwise, the team will need to find some personnel to fit the system. To be fair, the linebackers the team currently has are generally pretty bad in any system.

Now, as to the secondary. This is obviously a big concern for the Jets after this past season. The Seahawks under Quinn run a number of different formations, but use a significant amount of Cover 3. They usually have free safety Earl Thomas prowling deep between the two hashes, and a cornerback outside the hashes. They may press the wide receiver and then bail to their zone, or they may start in more off coverage. Dee Milliner will probably enjoy this role, as he has played his best when he's in zone coverage. The linebackers will usually take the middle of the field and the flats.

The other safety, the strong safety, can play near the line of scrimmage and focus on the run. The Seahawks use Kam Chancellor for that. Here, Calvin Pryor would probably excel in that role, as it's essentially what he did in college. The free safety has to be rangy, they have to have great ball skills. It's the lynchpin to the secondary. The cornerbacks need to be strong, physical, and excellent at tackling.

That was exhausting. That's the 4-3 Under in a nutshell, and it's probably the main scheme that Dan Quinn will bring over if he does come to New York. Please let me know if you have any questions below.