When the roof closed, I've not seen Federer play that well since nor for a considerable period beforehand. I remember being impressed by his performance against Nadal at Indian Wells.
Every time I watch him play, I'm surprised by the amount of power he has lost. He used to bang forehand winners from absolutely anywhere on the court.
Roger played well all year last year, except from the USO onward. He played well from the 2011 indoor season onward. So for a year he was playing really well and consistently. I don't see how he played better at Wimbledon or IW. It was the same level throughout. He hasn't lost as much power as you imply. He just hasn't played well since the AO.