I've been looking over the classes and notice that all the roles except for the controller have a certain mechanic. The defender's have their marks, the healers have their healing and the striker's have their extra damage boost but the controller is something that lacks this. Now AoE's do have a place in the controller classes but it's in the other classes as well. The only thing that I can really see that would be a controller mechanic would be zones. But does this really define the controller role enough?