Adjust the Back Foot 6/9/08
To find the right ball position don?t move the ball, move your back foot
One of the most common mistakes amateurs make in the setup is faulty ball position. Specifically, a lot of players move the ball around far too much, particularly when it comes to the position for a long iron or hybrid (hit off the ground) versus the short irons and wedges. The problem with this technique is that it forces the player to make alterations to the swing that often lead to an inconsistent swing plane and impact position. Instead, try to keep the ball positioned off your front peck (chest muscle), and simply adjust the position of your back foot. For longer clubs, move it back; for shorter clubs, move it forward.
"A consistent ball position will lead to consistent contact. Don’t move the ball around, but rather, move your foot."