I have been following this pretty closely, but maybe a true Giants fan can fill us in if I have it wrong.
Toward the end of spring training the Giants stated that since the schedule had so many off days in April, they would use Sandoval as backup and Holm was sent down. I haven't seen a definitive statement for May, but it seems like they plan to bring Holm up at some point and not have Sandoval be their only backup catcher. But I haven't seen anything definitive.
So far, Sandoval hasn't had an appearance at C, but they haven't had a long stretch of games yet. They play night games tonight and tomorrow, and a day game on Saturday. My guess is he gets the start at C on Sat.
I hope he gets 5 appearances at C, but right now I'm not sure that will happen.
There are a few things with the New York Yankees that never change. That's pride, tradition, and most of all, we have the greatest fans in the world. -Derek Jeter, 9/21/08 -- last words from old Yankee Stadium