Sunday, June 17, 2012

Chalk Talk - 3-4 scheme

By 68MD

Defense... Lots of talk about last years defense. Let's talk a little 3-4 defense.

At it's heart the 3-4 defense is pretty simple. You have three defensive linemen, four linebackers, two cornerbacks, and two safeties.

The requirements for players in a 3-4 are different than for players in a 4-3, and it all starts with the nose tackle. Joe Collier spent 20 seasons with the Denver Broncos and was the one who brought the 3-4 to Denver. Bill Belicheck has credited Collier with teaching him the 3-4 originally. This is what Collier has to say about the 3-4.

"You build it from the inside out," Collier said. "The nose tackle and the inside linebackers, those are three guys that are very important. But when you go through it, the nose tackle is probably the single-most important guy."

Your nose tackle needs to be a massive guy. Generally you want him around 6'0 or 6'1 and around 330lbs or so (the average size of the starting NT in the NFL in 2009 was 328 lbs), though nose tackles do come smaller (Jay Ratliff at 303 lbs) and much bigger (Kris Jenkins at 360lbs). His job is to tie up both the center and the two guards, preventing them from reaching the LB. If he does this, he's done his job. If he can collapse the pocket as well, even better since this means that the blitzing LB has a clear shot at the QB.

The DE in a 3-4 have similar jobs as the nose tackle. They are there to provide some pass rush, but mostly to tie up offensive linemen and force runs to bounce outside where the linebackers can make plays. In a 3-4 team your linemen won't generally have big stats--the fact that Cullen Jenkins did is a testament to his ability as a player. The pass rush comes from the OLB in a 3-4 based defense.

Your outside linebackers in a 3-4 were generally college defensive ends who are too small to play that position in the pros. You want them to be around 240-260 lbs. They have specific responsibilities as well. The weak side LB (the weak side of the line is the one opposite of the tight end) is the speed rusher. You'll sometimes see our OLB switching spots on the field based on the offensive alignment and this is why.

The strong side linebacker has a different job. He needs to be able to be strong enough to take on a blocker as well as quick enough to drop back into coverage.

Finally your inside linebackers need to be quick enough to get side to side in a hurry, though if the front linemen are doing their job it's an easier transition for them.

Very few teams run a 3-4 all the time, because it's difficult to get pressure on the QB in a passing situation (in fact that's one of the major weaknesses of a 3-4). To rectify this problem Dick LeBeau invented the zone blitz. Basically you have your three down linemen rushing the QB, and then one of your outside linebackers also rushes the QB. The rest of the linebackers fill the gaps in the secondary with help from the safeties and do so in zone coverage, rather than man to man. The cornerbacks will still generally play man coverage. On almost every play at least one of the linebackers is rushing the quarterback, sometimes two or three.

A big disadvantage of this scheme is that it leaves you vulnerable across the middle to seam routes from tight ends (Owen Daniels anyone?) as well a vulnerable to the screen since one of your OLB is caught up in rushing the passer.

So with that little review why all the issues last year ? Simple put the DL did not tie up blockers consistently and allow the LB to make plays.

AJ Hawk stated this week " “Watching film I felt like I got stuck on blocks a little too much,” Hawk said Thursday after the team’s mandatory minicamp concluded. “When I was able to blitz, a lot of times I’m blitzing up the middle or going against a center or a guard, and I feel like I got Velcroed or stuck to them a little too much. So I’ve focused on working on my hands and getting off (blocks) and get to the ball more.”

He should not have to worry about shedding blockers ? The staff MUST get our backers free of the OL and making plays. Keep an eye on our DE/NT early in pre season to see how they engage the OL and if our LB are flowing more freely to the ball.

If the DL improves so will this defense.

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