The barrell remains inside and above the hands. Keeping the back elbow in will keep your swing shorter and allow you to hit with more power. After impact the hands and bat extends right back at the pitcher while the palm of the top hand stays up as long as possible. Extend the arms back to the pitcher as far as you can without losing balance. Then finish the swing.
Most hitters are in too much of a hurry to finish their swing.
Make sure all of your force is going towards the pitcher with the swing, not back towards you. This minor correction in your swing will result in better bat speed and more power. Back knee facing the pitcher 2. Chin on the back shoulder 3. Heel to sky 4.