Z is the Opening Day starter. But depending on how the WBC works out, he may not be able to pitch on Opening Day.
Maybe Woody can do it again if he is ready to or maybe it's Mark Prior's turn to do it. Maddux would deserves it since he has been very reliable but putting him first might not be the best choice. Or maybe for some reason you think it will be someone else.
Z is the one that deserves it the most of course, but who should or will get the ball if he can't?