I do not understand Aarons' thinking on Thor. IF the phoenix force is his mother then you possibly have the most powerful Thor ever yet he cannot beat an egg. There was a line from Stark asking if the Avengers are so mighty why are they getting weaker? I only glanced through the issue so that may have been out of context as to whether it had any real significance.
He said we started all this with the most powerful group of Avengers ever!
So why do we keep getting weaker...
It was said because they were losing members to different circumstances! Had nothing to do with their actual powers and abilities.