CADAD
I am interested too . My son is strong upper body and slo-mo shows that his hips slide at times and he is mostly arms from the right side. Goofing around LH his hips turn through ahead of the shoulders good.
The answer to many shoulder problems is two fold IMO
Getting the hands loaded to come out in a circular path and having the hips turn to completion leading the hands.
I think flying shoulders are upper body hitters that are not connected and torque driven. Hard to correct once ingrained.
I plan to try some things this week. One is to put the hands in a pattern in front of the head going into toe touch to slow them down like: seen in Kirby Puckets swing and many others. Mankin calls this THT??
http://flippen.videos.home.comcast.net/Puckett1991MIN_HomeRunLF01.mp4[I'll let you know if it helps or is a disaster