I would say he is. I mean, he didn't really face a real challenge in the USO until Wawrinka, who almost beat him, and then Nadal did beat him. And Nadal has handed him defeat in two of the last 3 hard court events. So, unless Nole brings up something that we haven't seen since the very early part of this year, I don't see him taking this year's WTF.
As far as Murray, I can't see him bringing much to the table either. He still seems exhausted from the first part of the year. He made the finals of the Australian, won Miami, won Queen's and Wimbledon. That's a good year. But he hasn't really done anything since, and I don't really see it being likely for him to surge back to form for the WTF. But like you said, we'll see how he does in the upcoming hard court events, and we can gauge where he is then.