"As I came out of the box, it just sort of grabbed at me a little," Headley said. "It's just a freak thing."
Headley missed time in Spring Training when he strained the other calf during an infield drill. The Padres were cautious with him then because they could be. But he'll need a DL stint this time, even if this doesn't feel nearly as bad as the other calf did.
"My guess is it's not as severe as that was," Headley said. "I expect it to be two or three weeks. I guess the silver lining is it will help the rest of my body heal."
Headley has been battling a sore left knee, the one he had surgery on in October, as well as a mild biceps strain.
Headley was replaced in the field by Alexi Amarista, who will likely get the majority of playing time at third base. The Padres added Minor League infielder Jace Peterson to the roster. Peterson has been playing for Double-A San Antonio, and he saw some playing time at third base during Spring Training. He was hitting .311 for San Antonio with one home run and seven RBIs.
Headley entered the game hitting .188 with two home runs and seven RBIs. Two seasons ago, he led the National League in RBIs (115) and finished fifth in the NL MVP Award vote after hitting 31 home runs.
Headley was asked after the game if he felt snake bitten, if not for his poor start offensively this season but for the preponderance of injuries that he's incurred thus far.
"In my career, I've only been on the disabled list twice, and those were for broken fingers," he said. "There's no feeling sorry for yourself."
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.