Coach, spine angle (posture) is the only way MLB hitters determine the swing plane.....
"Short to it, long through it" is a total fabrication.....MLB hitters swing the bat to a point in space where they believe the ball to be by the time they get the bat around....They release all the batspeed they possibly can at ball contact.....Only thing left is some swing momentum.....
Any hitter trying to be long through the ball (I have a problem even saying that) is losing efficiency in a big way.....They max their batspeed after the ball is hit, waste their batspeed, and can't transfer swing momentum properly.....
MLB hitters do not hit through the ball....They hit to the ball......They have alot of tension in their body and their hands go soft at ball contact......