Troy hasn't been a jock since episode 4 or 5. They jettisoned that part of his character awfully fast, to take advantage of Daniel Glover's nerdiness. And Britta's development has been great -- from a strong lead "heroine" counterpoint to Jeff, she's become a person who is pretty much always stridently wrong. You Britta'd that review.
I'm not saying they're all bad. I'm just saying that it's like they took one aspect of the character and just made them that one thing.
My point on Troy was that he used to say silly things here and there, but now they have him basically believing childlike things and borderline retarded at times.
Just like Pierce who was always kind of the crotchety old man with racial/sexist undertones, and he blew up into a full on racist a-hole. Now, that could be partly Chevy's fault IRL, but his character is now solely what used to be only a part of Pierce.
I do agree with Abed/Troy being the lynchpin to the show though. That relationship seems to make/break a lot of the group's actions and reactions. That kind of exploded last year with episodes like the Pillow Fight and whatnot.
As for the writers/new show-head, I'll give them more than one episode before I say that things are too different or that they don't get Abed. I am hopeful that they'll do well.