Nadal 2011 looked positively bored out there against many opponents in the lower rounds, almost jaded and just kind of went through the motions, not to mention his many second set dips. There was rarely lack of focus from 2005 Nadal.
Of course you get bored after winning so much. The same with Fed. 2005 Nadal was young and ambitious. The mature nadal today is less energetic, but still he's more of a complete player than in 2005.
BTW, Nadal on clay in 2005 < 2011. And I'm a Fed fan.