You don't turn from a good player into a bad player just like that.
Yes he hasn't been the same since his return from Liverpool, he started last season ok, but soon found himself down the pecking order and shipped out on loan to Celtic (the team booze up Keane organised behind Redknapps back may have had something to do with that) anyway he returned to Spurs again this summer and had a good pre-season scoring frequently, but since then, yet again Robbie has found it hard to make the 1st 11, even thought he has been a regular for his Country. So he still has some of that Magic Vindo mentioned.
I believe he needs games (like every player). With regular football, Keane will surley bounce back and find the goal trail again, but i fear he won't get regular football at the rate he needs it at the moment. What i'm trying to say is he needs 3 or 4 full 90 minute games, not just cameo roles he and there as Harry looks to keep Pav, Crouch, Gio and VDV happy. He seems to have neglected Keane in my opinion.