Bending the Right Arm
One of the reasons you might have problems controlling the distance of your shots because you are hitting the ball too far is because even though you might make a great set up, you might make a perfectly balanced backswing, [is] on the downswing you bring the club in closer to you by bending your right arm more on the downswing, narrowing your arc, creating an explosion through the ball.
Try Widening Your Swing
Byron Nelson used to call this move a cow’s tail, where on the backswing you actually bring the club in closer to you, down cock it, increase the angle even more, and then release it very quickly through the ball. This makes the ball explode but it is very difficult to control the distance. To control the distance what you would rather have is a downswing that is wider. The way that you achieve this wider downswing is by straightening the right arm sooner. As you feel like you are straightening this arm you use a lot of the potential distance that you have built up more gradually through your swing so that when you arrive at the ball you have a more manageable speed. A real good exercise to help you to do this is the right arm only drill. Nick Price used to have this problem and used this drill a lot to try to help him overcome it.
Right Arm Only Drill
What I would like you to do is put the ball on a tee, take a short iron, grip the club at the normal length and then practice hitting shots just with your right arm only, clipping the ball off the tee. This will help you get that wider feeling. Let me demonstrate. As you can see that looked like a much wider downswing right there and a much more manageable distance. By hitting enough shots that way I will soon get the feel of having the downswing arrive at the ball with a more controllable speed rather than with an out of control speed. This helps me to hit the ball a little bit more controlled and shorter.