Originally Posted by luvforty
I should have clarified a little -
here he talks about the finish of a slice serve, so I guess another way to ask the question is do you finish (when the hand comes down to waist level) with
1) hand facing body? (or more extreme case, facing the ground)
2) hand facing the sky?
In this video that you posted he says that you do
pronate on a slice serve, you just don't think about it. It's at 3:55
Here's the link: