hold the golf club in ur left hand. swing the club back and through. now, let the arm and club hang downward freely. THAT IS THE LOW POINT IN THE SWING.... the only way it is lower is if the left shoulder gets lower to the ground.
basically, the left arm always swings and it swings from the left arm pit. ideally, ur ball position should be one inch behind the low point to insure a downward blow to the ball.
simply, place ur ball position one inch behind ur left pit, one inch back from ur left heel, or under ur left ear. whatever is easier for u to identify.
moving ball position back in ur stance creates bad mechanics as Brian Manzella already stated.
u can hit a quality shot with the ball back in ur stance, but it should look like a push to u.
u can hit a quality shot with the ball forward in ur stance, but it should look like a pull to u.
IDEAL BALL POSITION+GOOD MECHANICS+GOOD ALIGNMENTS=GREAT GOLF SHOTS!!!!