The show's priorities have changed. It's definitely evolved into character-based comedy, not gag-based, which means it's going to funny only to the portion of the audience that finds the characters themselves inherently funny. I thought the scene with Charlie trying to eat the eraser was one of the funniest things the show has ever done. But that's definitely character-based - there's no actual "joke" per se in it, other than that Charlie is the type of guy who would do something like that (and the very deft comic timing of both Charlie Day and the guy playing the principal).
Well, anything with Charlie is going to be hilarious. Honestly, I prefer THE LEAGUE at this point. Even a relative dud like last week's episode was leaps and bounds ahead of IT'S ALWAYS SUNNY IN PHILADELPHIA. Is there any word on that space-based comedy the SUNNY writers were working on, by the way?
Yeah as long as they have Charlie, the show will be worth watching. And the sci fi series the Sunny crew was working on appears to be dead...no news in a while...