Hardly comparable. Nadal played fantastic in W 2007 final and W 2008 final. He's not at that level now.
The only recent Rafa's match that kinda resembled that level was last RG final, where he also played unbelievable, but this time it won't be a final, nor clay.
The big if is Federer's and Nadal's grass form and whether it will go outdoor or indoor.
As for now, this match seems a 50/50 with no clear favorite.
What must Nadal do to become the favourite than? He reached the final of every tournament he played since his comeback. Yes, grass is different than clay. But Indian Wells was also not on clay, but on hard court. And he won that as well. It is just amazing how he came back after a long injury. Of course it will depend on the form of the day. But looking to the last months the form is very good.
Federer on the other hand is palying so far the worst year since a very long time. I do think he can improve. And win something. But is does not look like it right now.
At this moment Nadal is full of confidence, while Federers confidence is probably much lower. Altough Wimbledon may give him a little bit extra confidence.