You make a decent point in that some of John's best results come on slow courts because he has time to set up and use his explosive power! But what screws John is a medium pace court his movement will never be on par with the say Novak or Rafa so it's hard to control the points by playing the right way with attacking tennis! To be fair there are barely if any lighting quick courts any more but just looking at how John's game would work on such a surface and you have to like his chances, movement wouldn't be an issue as his serve would be very difficult if not impossible to returning on an old school lightning fast court! Then if the other guy got nervous and missed a few first serves John could take some big swings and jus needs one break and the set is as good as his! Or win one point on the other guys serve in the breaker. This is why the tournament organisers are wrong to not exploit this and prepare a an abosolutely lightning fast deck! It would have rewarded attacking tennis and prevented yet another battle of attrition!