It's by now common knowledge that showrunner/creator Dan Harmon was relieved from his duties by the NBC overlords after season 3 because of his aggravated attitude towards them, his alcoholism and his unorthodox approach to work (which usually involves plenty of naps and screaming in between moments of narrative genius) and was replaced by former Scrubs execs Moses Port and David Guarascio for Community's fourth season, Suffice it to say that season 4 isn't anybody's favourite by a long shot, and has been much-maligned by the fans who clamoured for Harmon's unique voice to be reinstated on the show. Though most of the cast remained on board, the writing staff was largely different and Port and Guarascio's reverse-engineered approach to capturing Community's former spirit resulted in a stiff imitation of the wild, irreverent programme we'd come to love. The ratings were never anything to write home about, and the show's penultimate season did nothing to change that. It also didn't help that popular opinion was that Community had never been in a worse place creatively than it was then, turning some off the show completely.
