I’ve been watching quite a lot of tennis this year, and I’ve been noticing a tendency among many professional tennis players—particularly noticeable in women players, for some reason—to crouch down fairly low when waiting for their opponent to serve, and then straighten halfway back up just before the opponent actually serves.
This FTP Tennis page describes crouching down too low as a common ready-position mistake, borne out of people observing this precise crouch, but missing the player straightening back up.
For reference, here are two pictures of Novak Ðoković in the two positions in question, taken from the same page:
Given that the player usually ends up in a ready position which is almost identical to the position they were in before they crouched down, I can’t help but wonder why they do the initial low crouch at all.
Why not just go directly into the final ready position? Wouldn’t that be easier?