I thought there was a stretch of 4-5 episodes late in the season where The Office had a real good streak. But I don't think they were ever going to match seasons 2-3... those were two of the best seasons by a comedy, ever. Theoretically you could replace Carrell... but it'd be like replacing Sam on Cheers... just hard to imagine.
I haven't hardly watched enough of Parks and Rec... I've tried catching on to the end of this season of Community. I think it's hit and miss. But when it hits it's pretty good. Although I think they got carried away in the finale.