I just did some of the Landing quests, and noticed while at first, Garrosh seemed pretty cool, when he assisted the Goblins, and they express their thanks, he literally goes on to say he came to save the supplies the Goblins were working on, and even mocks them. Then he threatens them to get to work, by bringing Orcs to make sure of it. Then later, he excessively mocks Vol'jin for no reason at all, and when Vol'jin questions what his motives are, he orders his assassination. I mean wtf, he didn't even do anything.
But when you look at Cataclysm, he had almost none of these traits, and was at least honorable.