Hes coming off a good beat down from Nadal,is playing on his "worst" surface. I have to think the idea that he is no longer within a shout of nadal and the joker is putting distance on him for #2 is most likely in his head right now. He does have a 5-0 record vs Kolb but they have never met on clay.
I could be barking up my own ass here..But it just seems like his time has passed and he might just say fukk the clay season and concentrate on winning Wimbledon..