But Posey will have to go on a slugging binge in the next few weeks to match his 2012-15 annual average of 20 homers. He began Thursday with 12.
Giants manager Bruce Bochy doubted that Posey's back, which occasionally has bothered the 29-year-old, has diminished his power.
"I know it has flared up on him occasionally," Bochy said. "He hasn't really complained about it. ... It hasn't been an issue with him for the most part."
Lack of power has not been limited to Posey among the Giants. They entered Thursday with 27 homers in 36 second-half games, tied for last in the Major Leagues with Kansas City.
• Bochy reconfirmed Jake Peavy will start Saturday's game against Atlanta. Peavy was reassigned to the bullpen when the Giants obtained left-hander Matt Moore shortly before the Aug. 1 non-waiver Trade Deadline struck, but Matt Cain's back injury presented Peavy with another opportunity.
• Cain is expected to make a Minor League start on an injury rehabilitation assignment soon, though Bochy wasn't prepared to divulge a precise date.
Chris Haft has covered the Giants since 2005, and for MLB.com since 2007. Follow him on Twitter at @sfgiantsbeat and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.