well 2-3 zone is complicated, and i don't think it is that much related to shot blocking. But, the way I see things, in order for this tactic to work, you should have players in the 1,2 positions extremely high in OD, the center extremely high in ID, and 3,4 should be very balanced defenders(at least 10 in ID and OD or smth). I mean think about it, when you play against such a zone you always pass your way out of it, in to the corner to move the defense around, and if the guys in position 3,4 aren't able to successfully go to the perimeter and then back inside(thus the multitude of layups), 2-3 zone is useless.