Duffy was batting .253 in 70 games, contrasting with the .295 average he recorded last season when he finished second in the National League Rookie of the Year balloting to Chicago's Kris Bryant. But Duffy was beginning to recover, batting .349 with seven RBIs in his previous 12 games.
"We're a couple of big guys down now," said Giants first baseman Brandon Belt, lumping Duffy with sidelined right fielder Hunter Pence. "We have to dig down deep. Everybody's going to need to step up a little bit."
"Everybody" is likely to include outfielder Mac Williamson, who appears to be a leading candidate to fill Duffy's roster spot. Williamson, who already has been summoned for three stints with the NL West-leading Giants, bats right-handed. His presence could help correct the imbalance of the Giants' lineup, though how much he'll actually play is questionable.
"If you saw tonight, we were pretty left-handed," Bochy said.
Ramiro Pena and Conor Gillaspie likely will continue to replace Duffy at third base. Pena's a switch-hitter, but the more experienced Gillaspie bats right-handed, so a platoon is likely.
Shortstop-third baseman Christian Arroyo, the organization's brightest position-player prospect, won't be arriving in San Francisco yet. General manager Bobby Evans indicated that Arroyo, who's batting .285 with two home runs and 20 RBIs in his first 62 games at Double-A Richmond, needs further Minor League experience.
The Giants will seek a second medical opinion regarding Duffy, 25. Regardless of that result, he sensed he must be careful not to resume playing before he's completely healthy.
"If you come back too soon, even if it is fully healed, it's weaker because you've been off of it," Duffy said. "So there's going to be a healing period and there's going to be a strenghtening period."
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.