GeorgeLucas, moving the front foot & the whole body forward 1.5 feet or so would seem to be much more than just a
slight movement of the feet. It also appears to be more than one foot moving as the back foot pushes off the ground at the same time. This looks more like a step and a half before the upward leap. Is this walking? I would say yes, but this is really a gray area. The movement of the feet advances his body forward to the baseline before he jumps -- to my mind that is still walking. But then we might just be arguing semantics here.
... you can see on the vid that he starts on a still position, he only moves his front foot, not the back one, so not really a step, then jumps.
I dont see a difference with other serves, for example, marcelo rios, and others, who drag their rear foot to the front, then jump, much less of course, to make contact.
As he
steps toward the baseline with the front foot, his back foot also moves (pushing off the ground) giving him a very pronounced
forward momentum before launching himself off the ground (as
tennisdad65 points out).
The other examples that you mention do not have the whole body moving forward significantly as the back foot slides forward. There is considerably less forward momentum prior to the leg drive upward. The forward momentum that we do see for these other servers is not a result of "walking" up to the baseline line -- it is a result of the back leg pushing up/off slightly before the front leg.
SystemicAnomaly: I realize you disagree with the rules, but the ITF does not...
Also, you are interpreting "position by walking or running" as "body position". Do you see why this is wrong?
No, I am not in disagreement with the rules at all, I am disagreeing with the loose interpretation (or lax implementation) of the rules. No, I do not see my interpretation as wrong. I see my interpretation as being stricter than the officials that have deemed it as ok. Are you saying that the ITF, as a collective body, has given the ok for this service action?
I am saying that the step & half that he takes after the toss constitutes walking toward the baseline. you may disagree with that since we don't have a clear definition of walking (is it more than 1 step? 3 or more steps?). For a volleyball jumps serve, we usually see the server taking several steps prior to jumping. This appears to be an abbreviated version of the volleyball jumps serve.