The Office fell off season 8. I still watched but it was bad. There were moments, but they were few and far between. The Office is still the GOAT, even with season 8, and 9 being terrible.
Seasons: 3=4=5>6(underrated)>7>2>1>>>8=9
Community fell off season 5, especially when Donald Glover left. I didn't watch season 6 until maybe a year or two after release, because the odds were it would be bad. To my surprise it was great. Community can make a five star episode in one room. They always found a way to be funny. Even with the least amount of budget, and network not having faith in them with low ratings.
Parks & Rec NEVER fell off. It's 100% (and i've always said this ) the most consistent, and they had 7 seasons. Great all the way through. I can tell the cast are like best friends IRL.
NBC was on fire at the time.
Never watched 30 Rock