Originally Posted by isilra
So we can say the loop itself theorically doesn't increase the racquet head speed but the benefits of loop like racquet positioning, timing etc. does ?
Yeah, that's the idea.
Take my musings with a grain of salt (and refer to the more experienced/knowledgeable posters here
), but this is what seems logical, as you correctly pointed out that the momentum of the racquet during the loop does come to a halt (passively, of course, Nadal doesn't consciously stop it while swinging).