justrelax, on 19 September 2011 - 01:20 PM, said:
It has to do with balance. Out of a three-point stance you can go in a variety of directions. Out of a four-point stance you can only go one way, but you can get all your weight forward and get off quicker. Because the wide-9 commits to getting off fast, the four-point stance works. Generally, D linemen use a four-point stance only when they're in a short-yardage situation and they want to get under the O linemen.
Bingo. It's the same reason why OLBs in the 3-4 typically use a 2-point stance. For a 4-3 DE, the 3-point stances are common if the DE ever has to drop back into a zone or swing out laterally to cover a RB in the flats. Since the DEs in the wide-9 never have to do this (since they only need to rush forward), they can use the 4-point stance to gather their forward momentum quicker.