Originally Posted by OTMPut
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.
Head YT IG Radical "Pro". Solinco Tour Bite @ 48#. Custom AK 90 pallets via 1stServiceTennis.com!! 28"/404 grams/18 pts HL/378 SW. And...denounce.