Ordinarily, the Giants would drop a reliever while adding Affeldt. But each reliever viewed as most vulnerable to a demotion -- right-handers Juan Gutierrez and Jean Machi and left-hander David Huff -- has no Minor League options remaining. Any of the three would have to clear waivers before being sent to Triple-A Fresno.
Bochy did not rule out the possibility of using a 13-man pitching staff and dropping a position player.
Affeldt, who has been sidelined since late March with a sprained right knee, threw off a bullpen mound Tuesday.
Marco Scutaro's status remained unchanged, as Bochy related that the second baseman has continued to perform baseball-related activities while coping with his sore back at the Giants' Scottsdale, Ariz., training complex.
"I don't have a target date for [Scutaro's return]," Bochy said. "He's still having his really good days and days where he has to back off a little bit."
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.