Toly, Interesting definitely is a closed face before, during and after impact.
Maybe that is a slice or kick.
Looks different than this serve. Maybe this is a flat serve. ?
https://vimeo.com/53440915
I thought that Stosur's kick serve looked closed racket at impact but from behind it was not possible to be sure.
What are the angles on the racket face for each type of serve at impact?