Rockhold's 100% right that Chris doesn't have much athletic grace. Like a lot of large (white) guys he moves kind of awkwardly. Even appears kind of uncoordinated at times.
Not that Rockhold (or anyone I can think of at 185) will be able to take advantage of that. Weidman's awesome at using that awkwardness to his advantage. It makes him hard to read and in addition to the list of strengths from the TS he has a great sense of timing and a fearlessness that lets him apply his pressure game perfectly. He's also great at reading opponents, which plays into his timing advantage.