As others have said, it's purely a 'mental attack'. It hasn't worked on everyone (Sonnen), but it's a solid way to throw your opponent off of his game without actually doing much work. He broke both Forrest and Bonnar with a few dodges and waves of the hand. Not many men can do that. I obviously feel badly for his opponents, as Bonnar will now surely retire and Griffin hasn't been the same man since, but hey... if you've got the gift, use it.
Some men break you with their endurance. Others break you with their wrestling. Silva breaks you with his mind. It is what it is.