A lot of coaches in the NFL are currently switching to the 3-4 defence. The trickle down effect is that a lot of coaches in Middle School and High School are switching to the 3-4 schemes as well.
Why the change?
A lot of coaches like the way the defence has the ability to pressure the offence by showing many different looks, blitzes, and stunts. With only 3 down lineman, you can mask different coverage's and bring blitz's from all over the field confusing the O- line and quarterback, pressuring them into making mistakes, creating fumbles and turn-over 's. The defence also allows you to maintain good downfield coverage versus spread offensive packages as you have the extra backs on the field to adjust.
There are drawbacks to this scheme.
First of all you need to have a solid Nose-Tackle who is a football player and is strong enough can take on the double team. If you haven't got one of those guys, you're in trouble, especially against teams that like to zone-block. By zone-blocking they will double team one of the D-lineman at the point of attack and then one of them will chip off and get one of your linebackers. Or they will down block in the same direction get all the defence flowing in one direction and try to "wash down" the defence while the running back looks for a cutback. Your Nose-Tackle is more vulnerable to the double team and if he cannot take it on, then it will create problems for your middle linebackers.
This is usually what knocks you out of your 3-4 defence.
I like the 3-4 defence. When things are going good you can pile up the sacks and fumbles. But beware of the downfalls. It's a good idea to have a 4 man front somewhere in your defensive scheme to counter against a good zone blocking offence.
Cheers
Why the change?
A lot of coaches like the way the defence has the ability to pressure the offence by showing many different looks, blitzes, and stunts. With only 3 down lineman, you can mask different coverage's and bring blitz's from all over the field confusing the O- line and quarterback, pressuring them into making mistakes, creating fumbles and turn-over 's. The defence also allows you to maintain good downfield coverage versus spread offensive packages as you have the extra backs on the field to adjust.
There are drawbacks to this scheme.
First of all you need to have a solid Nose-Tackle who is a football player and is strong enough can take on the double team. If you haven't got one of those guys, you're in trouble, especially against teams that like to zone-block. By zone-blocking they will double team one of the D-lineman at the point of attack and then one of them will chip off and get one of your linebackers. Or they will down block in the same direction get all the defence flowing in one direction and try to "wash down" the defence while the running back looks for a cutback. Your Nose-Tackle is more vulnerable to the double team and if he cannot take it on, then it will create problems for your middle linebackers.
This is usually what knocks you out of your 3-4 defence.
I like the 3-4 defence. When things are going good you can pile up the sacks and fumbles. But beware of the downfalls. It's a good idea to have a 4 man front somewhere in your defensive scheme to counter against a good zone blocking offence.
Cheers