Originally Posted by Satch
it's not that... just the question if he is so good with 90in how would he play with 95 (if we all know how easier it is to hit with 5in bigger frame)... and it leaves us speechless to even imagine how good he can be
but maybe it's stupid thinking and can lead to even worse game...
There lies the fallacy.
The improvement from switching from 90 to 95 is significant for an average club player. The less accomplished, the more is the relative improvement.
At Fed's level there is little he could improve. It might reduce his shank % by say 5 to 10. He would also lose elsewhere -feel, control (esp with his whippy wristy forehand). He might put more balls into play from his backhand side. That does not mean he would automatically win those points. It is not a straightforward sweet spot math.
I am sure he is smart enough to weigh up positives & negatives. Apparently he switched from 85 to 90 once. I am sure he would again if he think that would make a positive contribution.