Alias

Alot of the shows mentioned here are still doing really well in the ratings. People can nit pick and say CSI sucks, Grey's Anatomy sucks, but there are still almost 20M Americans watching them. But, the one show that took a huge hit was The OC. After a solid season 1, the writing in season 2 and 3 turned the show into a night time soap opera and the ratings suffered.

Even Season 4 which was a strong creative season couldn't save the show.

I know nobody will probably agree with me, but this question is a no-brainer for me: Arrested Development.

The first half of season 2 was as funny a run of a show as anything I've ever seen and then the second half of the season was unbelievably bad. I went from laughing so hard I was crying to not getting a single really good laugh from that whole run. Season 3 was a little better than the second half of 2, but nowhere near as good as it should have been.

I wasn't a huge fan of Angel Season 4. I mean, I love both shows in the Buffyverse, but I didn't the story arcs in S4 that much.

You will get absolutely NO argument from me. I said it repeatedly during the season 3 threads. It just wasn't the same show. The stories got lame (Charlize's arc was beyond cringeworthy) and characters (especially GOB) just seemed like bad caricatures of their true selves.

Still not as much of a nosedive as Battlestar Galactica though IMO.