Did Unaware do this for Quagsire in the long run? I'm sure after some time, it's usage will drop. Oh, yeah, and by the way,
252 Atk Tough Claws Mega Charizard X Flare Blitz vs. 252 HP / 252+ Def Clefable: 223-264 (56.5 - 67%) -- guaranteed 2HKO after Leftovers recovery
Why is this relevant when it can stop Dragonite, you ask? Well, the point is that Unaware Clefable stops set up sweepers for stall teams. If you can't stop MegaZard, you'll have to run a different check, and chances are that check will handle D-nite as well.
Yeah, yeah, it has it's niches, and I'm not disgusted by the idea of someone using it in OU because it fits well onto their team, but I feel like it's being used more then it should be. It's certainly not OU material.