Once the front heel strikes and the weight has shifted into the front leg the hands and upper body begin to rotate toward the ball.  It is this rotation that delivers the bat to the ball.  The front leg acts as a solid post which allows for a powerful rotation to the ball.  The bat knob goes from pointing at the ground behind the hitter to pointing at the ball extremely quickly.  Some general rules of thumb of getting to contact include:

 

1.  The back heel being fully to the sky before the knob of the bat gets too far forward.  This shows the hitter has full 

     lower body rotation and creates tremendous torque.

2.  The barrel of the bat staying above the hands and close to the back shoulder on the approach to the ball.

3.  The "flattening" of the bat as the knob points toward the pitcher.

4.  The body has tilt toward home plate

5.  The head, shoulder, hip and back knee are in alignment at contact.

6.  The hands are palm up and palm down at contact

7.  Depending on pitch location, the back elbow has a 90 degree angle and the front arm has some flex.

8.  The front leg is very firm with the weight from the back side driving aggressively forward into that leg.