Plus she was horrible on the show.

Delaney ‘didn’t fit’ CBS’ plans
The sudden departure of Kim Delaney from CSI: Miami didn’t just disrupt the show; it fueled tabloid stories that David Caruso had pushed her out.
Absolutely not, executive producer Ann Donahue says. “He was good to her and she was good to him.
“We never had one conversation with him about Kim. In fact, when Kim’s time on the show ended, he didn’t know it had been done. The network made the call, and then they called us, and then we called David.”
Caruso says the feuding-stars story makes no sense. “Think about the magnitude of who Kim is and her track record, and then ask yourself, ‘Would David Caruso have the power to disrupt a show that was this important to CBS?’ A show that is this valuable to the various parties certainly wouldn’t give the power to David Caruso to play around with the format.”
So why was Delaney let go? “It was just a question of fit,” Donahue says. “She’s an Emmy winner. She’s a gorgeous woman. She’s a very good actress. But when you look at the film, it just didn’t fit. And I think it probably speaks to how quickly we pulled the show together.”
Delaney’s spokeswoman declined to comment.