MYTH: Practice, practice your serve to get a strong serve.
REALITY: If your technique is not effective for a strong serve you will be learning the wrong muscle memory and technique. However, you will probably hit the ball more reproducibly and that may allow you to improve your serve's reliability and pace up to a point. First, learn an effective technique without any biomechanical flaws that would prevent an effective serve. Or hire a well-qualified instructor that can train the proper techniques.
This is one reason that I hate to practice and avoid it. Maybe an effective practice method using high speed video would be
to video just 1 - 3 strokes and immediately look at the videos and analyze them. Find flaws, they are very easy to spot. Make corrections. Repeat. Looking at videos of every 2 or 3 strokes is very, very cumbersome. Is it better to practice for an hour and then to go home and view the videos only to find that you never use leg thrust, or that your wrist has a bend in it that might cause injury.
For example, I think that this wrist angle at impact is wrong and stressful. This technique might have contributed to the slight wrist pain that I was experiencing at the time that the video was taken. Compare to pro servers wrist angles viewed from behind on other videos.
http://vimeo.com/21512296
Pro server.
https://vimeo.com/27528701
you´re right about the angle of the wrist. makes sense that it´s the reason for your wrist pain.
the old saying that practice makes perfect is wrong, imo.
practice of perfection makes perfect
there is a difference between understanding a technical detail on your serve and being able to change it effectively.
last summer i worked with a very good senior player who was unhappy with his serve. it was a weapon alright, but with a tendency to break down in a match. he couldn´t figure out why, and for me observing him from the outside it was clear from the beginning. his toss was erratic and too much to the right side, leading to a less than optimal contact point.
after some explanation and an hour of practice the improvement was clearly visible and he was happy.
he said that he would practice the toss by himself and didn´t take another lesson, as he figured he now knew the problem.
six months later he approached me again, because his serve hasn´t improved as much as he had hoped.
bottom line, it looks the same as before, no change at all.
we now work on a weekly basis.
his problem obviously is his muscle memory as you said in your post.
he has a less than optimal serve action but it feels right for him, and the improved action doesn´t. also, the body and mind tend to resist change.
the mind tricks you into believing that the change is huge, while in reality it is minute.
i try to work around that by doing lots of drills, that are not exactly serves.
for example i let him serve into the side fence, or from the service line, or start him from the trophy position,...,
what that accomplishes is, now it´s something different, and his mind doesn´t resist the new motion as much
sorry for the long post, couldn´t stop myself