I really like Kei and enjoyed seeing him demolish Rafa a year ago. And yes, Kieran, we know what would have happened if he didn't come up lame. Matches can turn, but Kei was totally dominating Rafa.
I'm surprised to see people say that Kei doesn't have enough weapons - I think he does. In a way he reminds me a bit of a Baby Sampras. What he seems to lack is stamina which makes me think he'll never win a Slam, but could be the best candidate outside of current winners to take a Masters (with Raonic and Dimitrov right behind him). That said, he did make it to a Slam final, so if he did it once he could do it again. As some have mentioned, he was out of gas by then - but I think he lost more because Cilic was playing at an absurd level. He was unbeatable, really.