Exactly! When I first saw that scene and Sam falls down, I thought Sam wouldn't have just gotten back up. And think of the ramifications if Dean hadn't gotten the info that Sam knew who and where the Kitsune was! After all, he didn't get that info until after the punch.

I would've been fine if, instead of killing Amy and lying to Sam and estranging him, there was instead more focus on Sam recovering Dean comforting and them rebuilding their partnership instead of being torn apart yet again.