The football defence of choice these days appears to be the 3-4 defence. Teams at all levels appear to like its diversity, its pressure, and its ability to cover most areas of the field. The 3-4 defence has emerged as an attacking defence capable of bringing the heat and providing good downfield coverage.
But what is its drawback?
Basically, my belief is that this defence is set-up around the nosetackle. If this defence does not have a true nose-tackle then things can become unravelled and exploited. A true nose tackle per say is a player with both good size and football ability that can take on a double team block effectively and not be scooped or washed down. But the key is the ability to withstand a double team block. What usually takes place on a nosetackle that cannot handle the double team block is that they will end up initially being double teamed by the centre and offensive guard and once their momentum is stopped or they began to lose ground one of the offensive linemen will chip off the double team block and go down and get one of your linebackers.
This brings up the point that an effective zone blocking scheme versus a 3-4 defence with a weak NT can be very effective. Double team the NT and chip off to get the middle linebacker would be the basic strategy.
Another weakness of the 3-4 defence would be misdirection such as an inside counter. An agressive nosetackle would definately "bite:" on the lead back and with the tailback cutting back to counter, with a trap from the OG on the counterside DT with both middle linebackers getting washed down with good blocking angles by the offensive line would definately do damage.
Coaching point versus the 3-4 defence. Test and attack the NT position. Look for the double team chip to middle linebacker and run misdirection plays such as an inside counter. Run the ball effectively inside and get them to switch into a 4 man front to counter the zone blocking double team.