What makes you think a returner who doesn't swing at all means him making a wrong guess? Have you considered that the returner just admitted his opponent aced him?
There are plenty of Youtube video highlights. Many of them record the aces, too.
While this is operating on personal bias, the kid I played had aced me several times during the match simply because I admitted it. I thought it was going to be impossible to reach. Similarly, when I aced him by kicking it off down the T, he just stood and admitted it. He hit some crazy serves that managed to snag the line, and so did I. I don't think either of us guessed the direction of the ball; we just simply knew that it was a genuinely fast, surprising ball that was practically low-percentage and unreachable.
I don't think I've ever seen professionals make moves before even seeing the ball head in that direction. It may seem like it, because they react so fast. For instance, I think Federer will see a ball bounce in a generic area, and move around to attack with his forehand accordingly.
This isn't an ace, but I think it demonstrates my point; Verdasco isn't moving prematurely here at all: http://www.youtube.com/watch?v=PnHLwjWUgIs
^^I think many people will agree here that Verdasco did a genuine split, read, react. No guessing, just shanking.
Another link here, probably describing what you see when a player moves around to hit a ball: http://www.tennisplayer.net/public/t...ro_return.html
As I described earlier, Federer moved back and went around to hit a forehand. You've probably seen Murray do this a lot to Tsonga during the 2012 Wimbledon Championships. Of course, I'm sure many players do this off second serves, but I'm certain it's not guessing or premature moving.
The webpage also states that players are simply in the air at the time of the service contact. Take a look at a professional match on TV, and this is very evident in nearly all returns, including Verdasco's return video above.
If it can't get any more clearer, you'll see that Murray is merely reacting as fast as he can, being in the air on contact, in accordance to the observation made in the article I posted: http://www.youtube.com/watch?v=SG2q_...=results_video