I don't think I said Segovia. Maybe you're reversing the terms supination and pronation, I'm not sure. Segovia, Bream, Parkening all did an amount of forearm pronation and also turned the wrist to the right and played off the left side of the nail.
What I'm talking about is the difference between the last two years of GFA winners. Check out
thibaut garcia 2015 GFA (right side playing in Presti style)
Xavier Jara 2016 GFA (left side playing with straight-ish wrist and supinated forearm)
This supinated forearm is becoming more common in modern players, some players still hold the hand like Segovia or Williams, but I've seen a lot of players not just playing with a straight wrist and slight pronation (like Barrueco) but with a straight wrist and a slight supination.
An eyewitness will often only see what he already believes to be true.