For your reading pleasure:
"The 3-4 Defense - Scheme and Personnel
1. With four linebackers, defenses can put more speed on the field to attack spread offenses. Also, coaches say linebackers are more bountiful than defensive linemen on the recruiting trail.
2. The 3-4 gives you the ability to adjust, to stay balanced and to adapt. If you’re playing a 4-3 defense, those four guys with their hands in the dirt are going to rush the quarterback 90 percent of the time. The 3-4 gives you versatility, and it's a little tougher for the offenses to predict where the pressure is coming from. It's harder for the offense to prepare.
3. Perhaps the most important cog in a 3-4 defense is the nose guard. He needs to be big enough and strong enough to take on double-team blocks, and he can't allow guards to reach the linebackers behind him.
4. A defensive end's role also changes significantly in a 3-4. In a 4-3 alignment, defensive ends line up outside a tight end or offensive tackle, where they hope to use their speed and athleticism to beat blocks. Most of the time, an end's sole responsibility is to rush the quarterback and collapse his pocket. In a 3-4, an end's most important job is to control gaps and beat double-team blocks to push the pocket.
5. Because their sole responsibility often is to take on blocks, playing nose guard and defensive end in a 3-4 is considered somewhat unglamorous. Ends and tackles won't produce the eye-popping stats they might get playing in a 4-3. More than anything else, their job is to free up linebackers to make plays.
6. The weakside linebacker (CAT LB) usually is the premier pass-rusher in a 3-4. But he also has to be big enough and strong enough to beat blocks from offensive tackles and running backs.
7. A strongside linebacker (DOG LB) often is asked to drop into space and cover tight ends and running backs on passing plays.
8. The two inside linebackers are supposed to find holes in the line and make plays in the running game or pressure the quarterback.
9. Coaches say the biggest advantage of a 3-4 scheme is its unpredictability. Any of the four linebackers can blitz on a given play, or one of the outside linebackers can move to the line of scrimmage as a stand-up end. the offense cannot predict where the pressure is coming from.
10. Finding the right players to fill roles in a 3-4 often is easier than finding 330-pound tackles, which are necessities in a 4-3. The availability of capable linebackers in recruiting is one of the reasons so many teams are moving to a 3-4.
11. Defensive tackles are tough to find. Defensive tackles are a premium [position]. When you do find them, everybody wants them.
In general, you can find the body types to play the outside linebacker position and they can play earlier in their careers. If the recruit has to play defensive end in the 4-3, you have to develop a guy strengthwise before he can contribute to your team. If a guy is playing outside linebacker, he plays in space, so he can rely on his athleticism and speed more.
12. New Notre Dame coach Brian Kelly switched to a 3-4 defense in his last season as Cincinnati's coach in 2009. He brought former Bearcats defensive coordinator Bob Diaco with him to Notre Dame. Even though a 3-4 defense might be more adept at putting pressure on the quarterback, Kelly says a defense's No. 1 priority still has to be stopping the run. And 3-4 teams will have to do it with one fewer lineman.
"I think what we need to see more than anything else from our defense is the ability to stop the run on a consistent basis," Kelly said. "Your inside [line]backers have got to be able to press guards; they've got to do a great job there. I know we can bring pressure from the edge with our athletes. We've got to be able to hold up inside out."
13. In the end, if a player doesn't carry out his assignments and tackle well, it really doesn't matter what type of scheme a defense uses.
Personnel for the 3-4
There are several intricacies that define a 3-4 defense but the biggest difference from a personnel standpoint, in teams playing a 3-4, is in the criteria for playing the "defensive end" position. Here is a closer look at exactly what we are talking about:
In the more traditional and popular 4-3 your ends are best suited for lining up in space and rushing the passer on outside the edge of the tackle. Those players usually weight between 260 and 275 pounds. The are athletic and agile and their strength is getting up field with quickness and lean. The ideal 4-3 end also possesses an ability to lean and turn the corner and squeeze the pocket in which the quarterback is standing. Teams are wiling to give up size and strength for speed and edge rushing ability. The perfect fit for this style of defender is Carolina Panther Julius Peppers.
On the other hand a 3-4 defensive end is more like a defensive tackle. He must be strong at the point of attack and is aligned in most cases head up on an offensive tackle and must control runs gaps first and foremost. Size and strength become more of a factor because he plays in confines of line play and seldom is in space using athletic ability. Ideally this guy should weigh 275-290 pounds and be able to beat double teams by getting a push. It's a more physical task then that of a 4-3 end."
