Or another popular term for this "jump the shark." What TV shows did you think went downhill after a certain point? Here's my list:
1. - After the movie.
2. - When Dil was introduced.
3. - Either when Dr. Kelso was no longer the head of the hospital or whenever the show started to focus heavily on the interns.
4. when original cast members (Kenan Thompson, Kel Mitchell, Lori Beth Denberg) all left the show.