Whatever you say. Because you know exactly how they feel when they hit with different rackets. Or because u have studied extensively the physics of their strokes with their current rackets and extrapolated to see if it would work with bigger size rackets.98 and 95 allow too much stretch in the string bed for Federer and Dimitrov's swing speed. They will have less control. This of course is with an open string pattern which both seem comfortable with.