"It wasn't that we wanted to put him in that spot," manager Rick Renteria said. "Based on the guys we had available, the two best guys we had were Anthony Rizzo and Starlin. ... It's not that I think Starlin is a prototypical fourth hitter, but based on the guys I had and how we use them, he ended up filling that slot for us."
Castro has batted second most of his career. But this season, he moved to the cleanup spot on April 25, and has stayed there.
"He's being Starlin Castro," Rizzo said of the shortstop. "It's nice to see. To be hitting home runs and driving in runs from the four-hole is nice."
A two-time All-Star, Castro trails only the Rockies' Troy Tulowitzki in batting average and hits among National League shortstops. Castro already has topped his 2013 home run total, hitting No. 11 on Friday.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.