The typical amount of carping from fans of The Mentalist about its announced move away from the Thursday 10pm timeslot, but if you figure that CBS's two best timeslots to launch a new drama are 10pm Tuesday and 10pm Thursday, moving The Mentalist makes complete sense.
But why move it to Sunday at 10pm instead of Sunday at 9pm (an hour with more people viewing TV, and where the best rated shows of the night typically slot)?
1. CBS puts an absolute premium on making as few changes to their schedule as possible. Likely a factor, but they did make other moves (CSI:NY to 8pm) that weren't essential.
2. CBS doesn't own The Mentalist (Warner Brothers does), and they do own The Good Wife, and still haven't been able to sell it into syndication, and they're going to do everything in their power to give it the best ratings they possibly can as they try and get it sold, current ratings consequences be damned.
I think it was probably 10% reason 1 and 90% reason 2.