Just to be clear.
Zone Defense: stay in the blue zone and wreak havoc until the robots moved to the white.
Man Defense: Follow 1687 around and make sure they have no chance to be of any sort of value to the alliance.
Like Hockey right?
Anyways, i think Zone defense will be more prevalent in matches only because it still allows you to be in the zone when necessary. i can definitely see a common strategy be robot 1 grab the ball shoot it to robot 2 over the truss then play zone D, robot 2 catch ball (or more likely grab it) and score then play zone D, Robot 3 slow down the Blue alliance (because our robot looks best in red so were red
). robot 1 and 2 may switch with robot 3 if 3 happens to be in a better position and also its robot 3's duty to also draw defense away from the ball carrier.(ie drive ahead and take the hit so robot 2 can move up) most robots will be very good 1 and 2's but i think its going to take a fast drive and great drivers to really get an effective 3.
just some food for thought.