New characters can extend a TV show's lifespan

Fans of "CSI: NY" were knocked for a loop last week when series star Melina Kanakaredes announced she's quit the show.

Actors leave shows all the time, and the only real surprise here is that it seemed to come out of the blue. And that, apparently, is because Kanakaredes didn't make any of this public until the announcement that she was leaving.

Her contract was up. Apparently, it was her choice not to renew it.

"We hoped Melina would return to 'CSI: NY' for another season, but we respect her decision to move on," said the CBS network and CBS Television Studios in a joint statement. "Her amazing talent and invaluable contribution to the success of the series are greatly appreciated and will not be forgotten. She will forever remain a friend to the network and studio and we wish her the very best."

And Kanakaredes issued her own rather simple statement: "I made some amazing and lifelong friendships during my six seasons on 'CSI: NY,' and I will treasure them forever!"

Would that all situations like this could be handled with so much class.

Fans of the show shouldn't be too worried, however. For one thing, CBS could hardly have found a better replacement than two-time Emmy winner Sela Ward.

(Ward won as best actress in a drama for both "Sisters" in 1994 and "Once and Again" in 2000.)

She'll join the cast in the season premiere "as an experienced investigator from Washington, D.C., whose work is driven by her empathy for the victim."

For a show entering its seventh season, this might not be a bad thing. And that is in no way a slam against Kanakaredes.

Like everyone else, television writers are human. And it's not easy to come up with new story lines for the same characters endlessly.

And the writers of "CSI: NY" are 140 episodes into the series at this point.

Often changing one character does more than, well, just change one character.

You can still argue whether "Cheers" was better or worse when Rebecca (Kirstie Alley) replaced Diane (Shelley Long). But you can't argue that it did not fundamentally change the show. And give it new life.

The series' producers themselves have said they doubted "Cheers" would have run for 11 seasons if it had remained the Sam-and-Diane show.