his forehand approaches were really bad because he would stop, hit then come in vs guys who would hit while moving forward. The latter approach allows you to get 2 or 3 steps closer to the net. Watch sampras forehand approach, edberg on the backhand slice they move through it while hitting so the close so much better.
The difference between closing on not closing is the difference between a good penetrating volley vs the Roddick block it into the court. His movement forward was just really bad, even off the serve.