Let me reformulate the question -- what kind of coaching would you be looking for being a top 10 ATP player?
I would say that a top 10 player will look first and foremost for a mental edge rather than a pure technical eye. Whether it is coming from the outside circle (Roddick) or from the family (Coria, Federer, Philippoussis). It seems to me that everyone in the business asked about it always talk about one thing -- confidence. Can you think of any player that would break the mold?