I don’t have a definitive answer, but this could help:
In high school, I spent a decent amount of time at the trainer and saw football players have similar tape jobs done to their joints every day. I know that for most of them it was to stabilize shoulders and prevent an exaggerated range of motion or a popping out of the socket.
Specifically, I play volleyball on a regular basis and I could potentially see why this type of taping could be used for hitters.
I wasn’t a trainer’s assistant or anything and I don’t have any extensive knowledge on the subject, but this could help: