The shoulders tilt AND turn. They tilt first as a result of you trying not to turn them and as part of getting the back elbow down, then they turn.
That's a pretty accurate statement, except that the bending of the spine isn't the main factor in making the back shoulder drop, it is the dropping of the back elbow that also lowers the back shoulder. Turning the knob toward the ball causes the shoulders to tilt. The lower spine at the L2 L3, vertebrae bends at the same time.
I agree. This is what "keep the front shoulder in" means. You resist turning the shoulders at first, but they DO turn, and they turn before contact.
I believe the barrel is thrown just after the shoulders lose their resistance and start to turn, which is after they tilted.
I agree that the shoulders quickly decelerate after the initial turn, but they do pull the hands, and they do turn or rotate.
You can say they resist turning, but they do turn, and that turn does make the hands move forward, which starts the throw of the barrel.
These guys all have their hips and shoulders fully turned toward the pitcher before contact. You can debate what they did to get there, but just prior to, or at contact, (not after), their hips and shoulders have turned.
