Frame #B -- Pre-Launch Mechanics
Timing Step (if desired)
The batter has started his timing step. The hips, lead-knee and lead-shoulder are beginning their inward turn toward the catcher from a more straightaway position. The hands are being pulled toward the back-shoulder (mainly by the top-hand pulling backward toward the catcher - "Pre-launch torque"), which causes the bat-head to starts its acceleration (sweep) from a more vertical position back toward its normal launch position behind the head.
Pre-Launch Torque - Barry Bonds
Hands go Back - Linear or Rotational Mechanics
Defining Linear and Rotational Transfer Mechanics