Some insight about this season from someone that went to the Communicon event.
More detail on the Nic Cage ep: apparently, Jeff was convincing everyone that "Film Appreciation of Nicolas Cage" was a real class, and the Dean found out. So, as punishment, he decided to actually make it a real class, and set the final in twenty-four hours, leading the entire study group to have to watch the entire catalog in one day. They would subsequently go insane.
Apparently the network needed Nic's approval, and he was off shooting Ghost Rider 2 or something, so they couldn't get it done.
It was a huge Chevy Chase hate-fest from the writers...they would intentionally write scenarios or situations in which they could isolate Chevy from the rest of the cast. There was a scrapped B-Plot at one point where Pierce locks himself inside of the campus radio tower for a day and does a bizarre shock jock-like routine.
Apparently there was a Sony exec named "Kim" who always gave them ****** notes. So some episode was written almost entirely to eventually have one of the characters say the line "No one cares about Kim's note." I don't remember which episode this is, though.
Dan Harmon was funny, but I could absolutely see why he could be difficult to work with. He had this air of...I don't know, I'm-so-****ing-wise, that I found a little off-putting. Still, brilliant guy.
I got to speak with [redacted: some writer here] personally for a good ten or fifteen minutes. (S)he told me about the real hamstrings on the writers this year...(s)he explained that while (s)he felt the show definitely took a downturn, it wasn't so much Dan Harmon leaving as a billion other factors, including the loss of half the crew, new directors, and most notably, Sony/NBC basically saying "**** you" to them at any available opportunity. They were basically prohibited from shooting outside, the network heads would say things like "you can have three extras in this scene, no more", they would send junior agents and newbies to give notes. And the worst part is when the head of NBC (Rosen-something?) spoke to the two new showrunners, the only time he ever did, mind you, he said "Thank God that show didn't win an Emmy, right?" as they walked in. Heaven forbid they would be wrong about a show.
(S)he felt confident that the Halloween episode would be good, and something later in the season about marine biology. But they did their best, and a lot of the core writers were still on staff, so there should still be moments of brilliance throughout.
Edit: Oh, and Garrett SOUNDS LIKE THAT IN REAL LIFE. The "normal" voice in the Greendale Asylum episode was actually Dan Harmon himself.