Yeah, probably, but who wasn't. That was just an explanation for the slightly off way many off the characters acted, not an overall plot point or tool for character development.

Chang is perfect again for two reasons
1. In season 4 it was revealed he'd caught something from Annie's Boobs (when they fought in the vents back in season 2's Paradigms of Human Memory) which caused temporary insanity. By the end of season 4 it had worked it's way through his system. Also, Abed's brief conversation…