I'm With The Brand
That there would be absolutely no change in rating after a headline-grabbing transition is unusual. Steve Ballmer didn't get it that easy when he took over Microsoft, and U.S. president approval ratings are, well, yeah. So what is it? Honeymoon phase? Halo effect? Good old-fashioned skill? Who knows, but I'm willing to bet as long as Apple maintains its current image, Cook too will continue to look good.
It's an interesting thought experiment at the very least. Have you seen other instances of company branding making (or breaking) its employees?