gutfeeling
Hall of Fame
I love all encompassing answers like this. You should let Tommy Paul, Alex DeMinaur, Mackenzie McDonald, et al. know this
ground breaking, definitive news.
Maybe they’re just not talented enough to use the 18x20?
I don't think we can assume they are currently using the retail 16x19 layups which are firmer than the 18x20s, with the exception of the v7 16x19 which is just as soft as the 18x20 but less weight in the head. I agree with @snoflewis that generally the retail 18x20 blades are superior to the 16x19s.