You'd think having the most successful show on cable TV ratings-wise would be enough for AMC. But over the weekend, the network announced that for the second time in three seasons, it will be replacing the showrunner for "The Walking Dead."

After dumping Oscar winner Frank Darabont after the show's first season, AMC announced an "amicable parting of the ways" with current showrunner Glen Mazzara, who has guided the show in Seasons 2 and 3.

Mazzara will be staying on through the end of Season 3, which continues this February, then head off to greener pastures.

AMC said it was because of "creative differences." How can it have creative differences in a show that has put up ratings that would be good for a network, never mind a cable channel? How can there be creative differences when "Dead" is on most critics' Top 10 lists for 2012? Why mess with a good thing?

It's not as if AMC doesn't have a history of screwing around with its showrunners, having had issues with "Mad Men's" Matt Weiner and "Breaking Bad's" Vince Gilligan. The only show the network has left alone was "The Killing" -- the only show it should have replaced the showrunner for, given Veena Sud's arrogance and lack of compelling storytelling.

This season of "Walking Dead" hit on all cylinders, and it'd be tragic if the show went off the rails because of the network's meddling.

MONDAY'S BEST BET: With reruns all over the dial, you may as well check out the holiday classic, "It's A Wonderful Life" (NBC, 8 p.m.).