I say it isn't pro stock. What you have there is a retail version ncode 6.1 95 16x18. The retail versions of the ncode line are matte in the red areas and glossy in the white just like your frame.
The "matte" pro stock indicator only applies to the kfactors 6.1 racquets. Keep in mind the kfactor tour 90 is matte and the current blxs are matte.
However there is something different about your frame. As you said the grip label says 4 5/8 but it feels like a 43/8. That is because it looks like the devious owner shaved the handle and did a pretty poor job at that. The grip looks uneven. But it might just be the leather grip. Correct me if I am wrong. They also used a cheap replacement butt cap instead of an authentic wilson one. By the look of the shape of the grip it looks like they shaved it all the way down to the hairpin. If that is the case, the racquet is going to be costly to restore into playable shape. Post a picture of the racquet handle without the leather grip so we can confirm this.
Wilson 2011 blx 95 18x20- polystar energy 18g @50lbs