I think the problem is people are too lazy to interpret the diagrams. The diagram explaining what flexion, ulnar deviation and pronation is so straight forward, but I think people get scared of the physiological name, that they refuse to memorize what they are. So when you have that diagram at the beginning of the long thread, they probably won't go back to the beginning of the thread, to recall what ulnar deviation is.
Well, the fault lays in laziness of the mind. I think it is very similar to someone learning chess and won't memorize a few standard openings or book moves.
Hey, I've been reading your comments on the forehand on TW forum. Really clarified what is giving power with Fed, Agassi (flexion) and Djoko (ulnar deviation, pronation). I've been playing around with that a month ago.
I don't see his fingers open out like a rock climber gripping a hold like those other pro pictures. He looks more relaxed. However, he is using the left arm as a brace or marker, but it never looks like tremendous tension in a open fingered "spray". But nice pictures, Anatoly.
I think the pros outstretch their other hand in order to "harden" the left side as an anchor so that the right side will whip through harder. What do you think of Federer who doesn't do that with his left hand, but tuck his left arm in and remains looking relaxed?
I will try to use a tighter grip today on the serve and see what happens. You might be right in that there is energy lost in holding it too loosely, and having the arm too loose. I believe there is an ideal angle of the elbow and there has to be tension building up in the arm to really pronate hard.
I don't hold the serve grip very tight, but slightly firm around the thumb and trigger finger. Before your article, I had held the racquet angled but leave the pinky off and adjacent finger very loose.
Now that I hold the thumb across and everything else the same,I am getting much better pronation on my kick. Also, hitting the first serve flat more sharply. I have been working on the Sampras motion for the last year. Your article explains the arm motion very well.
I recently posted an article here on the kick serve written by an Anatoly Antipin. It was originally posted on Tennis Warehouse forum. Are you the author? If you are, thanks for writing the article, it really helped my serve.