I agree I don't think 30 is all that old, even for tennis. Especially for somebody as truly great as Roger. People like him tend to break a lot of those types of rules...
It's obvious he's far from playing at 100% of his abilities (not saying he's injured I'm just saying he's not giving 100% effort), I don't think he's actually LOST any ability whatsoever, be it movement or his forehand or backhand, or whatever.
However I do agree with Chederer when he said that he doesn't slice his BH enough now...I remember the criticism used to be that he sliced the BH too much but he's tried coming over it and it doesn't work, he needs to go back to slicing every other BH.