See if this makes any sense. IF at the top of your backswing your on the correct plane, your wrist was cocked at the proper 9'oclock position, your grip is correct , and feet and shoulders are aligned down the target line, THEN starting with the arms tends to close the club face causing the ball to go left of target for a right handed swing. Starting the waist first with a weight transfer to the left heel opens the club face. Depending on the timing between the two body parts gives you the inability to recreate the same golf shot everytime, fatigue being a factor. When your are at the driving range you should notice that as the clubs get shorter the waist becomes more quiet. This causes you to aim a little more to the right to counter the ball flight towards the left.