Originally Posted by TheLambsheadrep
OK, I think it's because this picture looks like it was taken after contact, but I don't see why she couldn't use wrist radial deviation if the picture is of before contact to brush up on the ball. Since the racquet face is a little more angled down to the ground and pointing between 1 and 2o'clock out from her body, it would just naturally end with the wrist turning over so her hand would essentially be making a "thumbs down." Does that not count as radial deviation?
The wrist can rotate the racquet about two orthogonal axes. Djokovic palm is horizontal, thus wrist deviations can rotate the racquet about vertical axis only. In picture 1, from above view, Djokovic rotates the racquet counterclockwise by using wrist ulnar deviation and racquet moves forward. If he used wrist radial deviation, picture 2, the racquet would move backward, away from the ball.