Yes, I think so. A new coach would give him renewed motivation, a good kick up the arse. He seemed strangely content with choking the AO final and getting routed by Federer. Plus, how much time does he have left at the top? A bad clay season could be the end of him.
there is no question the time is running out. he has to make something happen in the next 3 years.
he needs a target of 4-5 slams in 3 years and then go about making it happen.
and to hell with the rankings now. he is not managing the rankings well at all anymore.