I can bet that the serve receiver has already narrowed down the destination of the serve from the pose/action/eyeline/aspect of the racket head/racket head movement/etc of the server.
Same in cricket, and in particular the advent of the slower ball in one day cricket. A normal fast bowler’s delivery will release the ball with a snap of the wrist and two fingers behind the ball, imparting spin on it. To bowl a slower ball, you don’t slow the arm down, you either snap less, or even more dangerous snap but allow the ball to come out between the fingers, so the action looks identical but the ball floats out. And makes you look very silly indeed.
[video]https://www.youtube.com/watch?v=e6gPMq9qOTM[/video]