Watching Federer: Backhand

As I'm looking at photos of Federer's backhand, I can see that his head is down and even turned back, and he's watching the ball from the corner of his eye, almost as if trying to avoid seeing it. I also read in the Tennis magazine that it used to be even more exreme, that on a backhand slice he almost looked back towards the fence. When I practice backhands, I sometimes try to turn my head down and a little back, and not following the ball, and strangely enough, it seems to work. It's very hard psychologically to turn away from the ball in this way, and in a match I forget to do it. Somehow I need to drill it to such extent that it's in the muscle memory and I don't have to think about it.