Many of you have heard stay inside the baseball. Well I got news for you, your always inside the ball. What you are actually trying to do is trick your hands not to cast by making your eyes focus on one spot.
The way hand eye coordination works is that the eyes lead the hands. So if a players is looking to stay inside he will actually hit the ball solid. It allows the motor skill a little room of forgiveness. If you focus on the whole ball you will hit the outside.
To practice this simply place the ball on the tee with the laces parallel with you (train tracks pointed at ceiling). Then try to hit the one closest. The important note is to focus on the inside part not aim at the inside part of the ball. If you aim your shoulder will pull out and hands to close to body.
Know the Why