How to compare JW and Ash?
Ash has coached juniors to big wins, but his own playing level is probably not that of a pro.
JW was a pro, and has coached players past the junior stage, in the ATP and WTA.
It is a tough call.
Richard Williams and Nick Bollitierri have produced great pros, but themselves probably never crossed the 3.5 level. Vince Spadea has not produced any pro, but his comments indicate he really understands the game due to his own high level of play.