Anyone who has ever written a novel, screenplay or whatever knows there are three basic elements to storytelling:
1. Storytelling (aka Style): The way that story is being unfolded. This could be slow and epic, this could be fast paced and funny. There are alot of stylistic elements going into this. And there isn't really a right or wrong. Season 1,2,3 of community had a slow but steady storytelling useing epilogues to create tention. Just try to keep this in mind
2. Character design: The way that characters are portrayed. Either they're a douche, or nice, or narcisistic (*cough* Jeff). This doesn't really change all that much because people rarely change. And if they do, it takes some effort on the part of others to make them change. Try to keep this in mind ;)
3. STORY! The actual happenings of what's happening ;) In Season 3 we had warmonger Chang, we had the Epilogue about City Colleges invasion, chang being connected to them and of course Starburns still being alive.
Now. Coming from somebody who has written 3 stand alone novels, tons of fan fiction and 5 of her schools theatre department productions let me tell you: YOU CAN ONLY CHANGE ONE THING AT A TIME!
You can either change the style of the show. Or you can let some of the characters evolve. OR you can abandon whole story elements and switch them for others. But you can't do all at the same time. You can do them one after another but not at the same time.
Season 4 did exactly that. They screwed up the style, they completely reinvented ALL the characters and they (mostly) ignored all the given plot elements from Season 3. That's why this season sucks! It's not because Dan Harmond isn't there anymore it' literally because the new writers DON'T KNOW HOW TO WRITE FUCKING STORIES!!! Period!
I will still watch this show because I apparently have nothing better to do and I'm hopeful that it will one day become better. But until then, I'll remain skeptical. I don't like what the writers have done with the show and until they try to norm themselves to end-season-3 levels and play the ball from there, I don't think I will.