For the past few seasons under Pete Carroll the calling card of the Seahawks has been their dominant physical defense, and in particular their secondary. Much has been made over the past few years about the size of the Seahawk corners and how they use their size to deny receivers with physicality, but the reason for those big tough corners goes far beyond that.
In order to really get why the Hawks do what they do let’s take a look at a typical Seahawks defensive alignment. (click pictures for large size)
The two things that makes the Seahawks defense different can both be seen here, first off one of the corners on each side of the field will play tight man coverage to defend the receiver who comes to their side of the field as Seahawks corners cover one side the whole game as opposed to moving around. Because the Seahawks defense can rely on their two (or three in nickel coverage) cornerbacks to lock down their receiver the Seahawks are able to bring Kam Chancellor into the box to act essentially as a fourth linebacker to stop the run or to cover tight ends.
To account for the fact that one of their safeties is almost always up towards the line Earl Thomas is dropped deep into coverage and given the responsibility of preventing long completions and is left largely to freelance and make plays on the ball in a similar role to what Ed Reed is famous for.
This brings us to the other thing that makes the Seattle defense special, mixed fronts. This year all the rage defensively in the league is mixed fronts but Pete Carroll has used them for years. to put it simply a mixed front is a combination of a 4-3 defensive front and a 3-4 defensive front. In a standard 4-3 there are four down linemen and 3 upright linebackers none of whom typically rush the passer on a non blitz. A 3-4 front features three down linemen and four upright linebackers, one or two of whom will frequently rush the passer. a 3-4 front is pictured below, compare it to the Seahawks defense above.
Pete Carroll’s 4-3 is a little different however, he uses a position called the Leo lineman (take a look at the Leo on the first picture, he’s way out to the side but is down instead of upright.) now look at this shot of the Seahawks defense earlier in the game.
Look’s an awful lot like that Baltimore 3-4 defense doesn’t it? That Leo lineman position is essential to the Seahawks defense because it allows them to play a very versatile defense which in essence features five linebackers as one safety and one lineman have linebacker skills and positioning in the alignment to allow them to use them in certain scenarios. That offset position that is shown in the first picture also helps to allow the typically smaller Leos to use their speed to more efficiently rush the passer.
These small differences have aided tremendously in the Seahawks dominant defense and they’ve already begun to be picked up on by some other teams, look for this kind of mixed front to be everywhere within the next couple years.