Fine, I bring in my Volcarona for free vs a -2 Latios. Your Scarf Terrakion is the only thing that can revenge me @ +1. Basically, you are forced to bring it in to revenge, and then I have an excellent chance to go for a trap with Wobb. Sure, the above scenario is subject to whether volc predicts Terrakion staying in against it but the point is clear, its easier said than done to keep your revenge killer back, and when against (or using an) offensive teams, trapping and eliminating the opponents revenge killer, is no small a thing. It becomes even harder when you use 2 pokemon that get revenged by the 1 pokemon, and sac the first one to lure in the revenge killer, wobb traps, and then the second sweeper can set up and not worry about getting revenge killed. Sure, taking damage to do damage sucks, but you are not picking up Wobb for that, you are picking it up for trapping and eliminating one problem pokemon that troubles your team, so that a sweeper of yours can sweep / set up more easily. Go see Gamestar's Sun RMT (BW1 but still) for an example of how Wobb can perhapes be used successfully.