Dima's serve still in discussion? If there is something to complain about, it is that sometimes he takes his arm away too late ( hard for the umpires to see). IMO the advantage of throwing the ball into his body is minimal due to the height of the toss.
I'm not saying it's a proper or improper serve, but the condition for that is whether or not it takes place within the bounds set by the rules, not whether or not it is advantageous or not. So what about these bounds?
The toss should be +16cm and "nearly vertical", and at no point while serving should the ball be hidden from view from the opponent and referees. Now the rules, afaik, do not define the angle range for "nearly vertical", so I don't think there's a firm argument to be made there; ample room for interpretation. The "not hiding" thing is also something, but that's also subject to human limitations. Lex non cogit ad impossibilia, law cannot enforce the impossible.
Perhaps this is my perverse mathematician's mind, but I think these rules are rather toothless due to the lack of rigor in the definition of the underlying notions. This makes me entirely unsurprised at seeing a somewhat haphazard and not entirely consistent implementation by referees. Leaving ambiguity, vagueness and room for interpretation will do that.
