There's potential there for sure.
His problem will often come against patient clay court specialists. Although he's improved his fitness considerably, I still wouldn't fancy him in a 3 hour battle with guys like Canas. He also doesn't have enough patience to go deep in a rally, though I believe Corretja is trying to improve that.
His game is ok for clay though, he used the angles well, is one of the best on tour at constructing points, and his movement is good enough.
He actually used to describe it as his favourite surface, he had a lot of success in the lower levels.
Canas actually isn't the main criteria of comparison, he has always been better on slow HC than clay.
That may be true (apart from Nadal), but there are plenty players with much better results on clay than Murray so they should be considered better clay court players than him.
All the results from this era on clay mean nothing because the field is awfully weak.