Giants top prospect Buster Posey enjoyed a successful debut on Saturday against the Diamondbacks. He had three hits and three RBIs in his first game of the season. He played sparingly during a brief call-up at the end of the 2009 season. "What a great job the kid did," Giants manager Bruce Bochy said. "I'm sure he didn't much sleep last night and then he goes out and gets big hits for us. It's something we needed." San Francisco defeated Arizona 12-1 at AT&T Park.