"It's a combination of things. First and foremost, I've got to swing at better pitches," Headley said. "I'm getting myself out. I'm making him [opposing pitcher] thrown one quality strike. And there has been a little bad luck mixed in there, too."
Headley is seeing fewer pitches per plate appearance (3.90) than any other time during his career and fewer than he saw a year ago (4.04). His swing-and-miss percentage (29.9) is also up from 2012 (26.6), when he led the league with 115 RBIs.
"When things happen like this, it's not usually just one thing," Headley said.
San Diego manager Bud Black said Headley isn't tracking the ball as well as he has in the past and went as far to call Headley's slump "uncharacteristic."
"I think more than anything, he's probably a little overaggressive early in the count," Black said. "The uncharacteristic early-count swings on pitches out of the zone. He knows it. And for Chase, I think it's frustrating because he knows that's not his game. Right now, he's swinging at pitches out of the zone."
According to Baseball Solutions, Headley's contact rate has dropped from 74 percent a year ago to 71.6 percent this season.
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.