Why can I not get back for the overhead smash?

the tennis player tends to face the net and backpedal this is reason they cannot get back to retrieve the Lob with the overhead smash shot. The players movement needs to turn and run back like a quarterback getting out after getting hiked the ball. the movement after being hiked the football iis not backing up, but he turns and runs back. This move back is really a challenge for the average player.