Originally Posted by Stringer_Steve
I can see that they probably use the same mold, but that isn't something that the manufacturer has ever disputed (from what I can tell). It's the composition and the people posting that they "know" it is this racket or that.
From the moment Wilson started marketing him as using the BLX they were effectively saying otherwise. He was using the K90 mould which was/is not exactly the same as the BLX they said he was using. They're very close but the subtle differences have been noticed and I imagine this will be the case with the new variant too.
We only know the progression of his frames and where the PJs happen relative to retail models... As for the internal composition.. that's where it comes unstuck. Personally, I'd guess his frames are a custom composition which retains their flex over the lifetime they are in use (3 months basically) - more consistently than a retail frame would.