Only seasons 1 and 2 were good.

Yah Carroll's character was more interesting. The third season just tried to hard but it didn't pay off

Agreed and the reason being is because Kevin Williamson was in charge of seasons 1 and 2. Which is why those two seasons were freaking awesome. He left after season 2 and that's why season 3 was so boring and terrible. The new show runner JUST missed what was so great about those first two seasons and turned season 3 into a typical boring cop show that was just plain boring. And having Joe Carroll having such a small role to the story was incredibly painful. He literally had like two scenes in each episode, both of which were no longer than one minute. IMO, that is what ultimately got this show cancelled.... No more Kevin Williamson. I'm willing to bet good money had he stuck around season 3 would have been way better and maybe, just maybe the show could have been renewed for at least one more season.

Seasons 1 and 2 literally had something shocking, thrilling, exciting, and some kind of twist in just about every single episode. Season 3 did not do ANY of that at all and that is what brought down the show. In seasons 1 and 2, you could basically guarantee something unexpected would happen by the end of the episode (ex. Mandy killing her mom instead of Joe, Claire stabbing Joe when they were slow dancing to music) and in season 3, you could basically guarantee NOTHING would happen at all by the end of the episode.

Kevin Williamson knew how to shock his audience. Season 3 show runner did not.

I thought season 3 was not a drop off in quality. Ryan was purposely avoiding Joe for a while and did you really want 8 minutes of screentime every week of Joe just staring at his cell wall? Also the idea of another Joe escape from his cell would have been unbelievable even by this show's standards.