With Brandon Belt entrenched at first base, Ishikawa is expected to provide depth in case of an injury. "It's nice to have guys with experience you can call on," Giants manager Bruce Bochy said.
With the Giants, Ishikawa hit .265 with 15 homers and 80 RBIs in 281 Major League games in 2006 and 2008-10. He played for the Brewers, Orioles and Yankees besides the Pirates after he left the Giants system following the 2011 season. San Francisco originally selected Ishikawa in the 21st round of the 2002 First-Year Player Draft.