"It's like each guy's got to touch the stove to find out," Bochy said. Casilla got burned by straining his right hamstring, sidelining him for an anticipated four weeks.
Bochy wished in retrospect that he had ordered Casilla, who was making his fifth career plate appearance, to do nothing more than stand in the batter's box when he faced Colorado's Boone Logan in Wednesday night's ninth inning.
"He was told before the at-bat not to swing," Bochy said. "[But] these guys are competitors and sometimes they forget."
Bochy added that after Casilla hacked at a 2-1 pitch, "I should have called time out and said, 'That's it. No swinging.'"
Bochy plans on reminding pitchers to be smart at the plate and on the bases. Injuries such as Casilla's have occurred too often with Giants relievers when they stray into the batter's box. Left-hander David Huff strained his left quadriceps earlier this season and left-hander Dan Runzler sustained a knee injury in 2010.
"Relievers live for that," Bochy said. "They want that one at-bat."
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.