Depth perception

The author of the tennis.com article I mentioned in the previous post also talked about the fact that you can improve your depth perception of the oncoming ball if you look at it sideways. For example, on a forehand, you look at the ball with your face at 45 degrees to the net, sort of askance. Then, you keep the head in that same position as you hit through the ball. I'm not yet convinced that looking sideways at an object improves depth perception, although intuitively it feels right (you basically add 0.7 of the distance between your eyes to the parallax).