Walker had played in all of the Pirates' first 62 games this season and started in the first 58, being held out of the starting lineup against the Padres last Wednesday for the first time before appearing for a pinch-hit at-bat in the eighth inning.
The switch-hitting Pittsburgh native is batting .280 with 35 RBIs and 11 homers. His RBIs are tied for most on the team along with Pedro Alvarez, and Walker has the most home runs of any National League second baseman.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Stephen Pianovich is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.