Matt Sosnick, the agent for Eric Hacker, announced on Twitter on Wednesday night that the Giants would be purchasing the contract of his client to fill that spot in the rotation. Bochy would not confirm that announcement.
"We haven't made any move yet, I can tell you that," said Bochy. "We don't have to do it until tomorrow."
Hacker, 29, is not on the 40-man roster. He is 4-0 this season for the Triple-A Fresno Grizzlies with a 2.19 ERA in 24 2/3 innings pitched. Opponents have hit just .217 against him so far.
The rainout last Sunday in New York hampered the San Francisco rotation. Bochy kept Tim Lincecum in his normal spot in the rotation by having him pitch the opener of Monday's doubleheader. Lincecum is scheduled to pitch Saturday against the Padres, with Madison Bumgarner slated to go Sunday.
The Giants next have an off-day Monday before a stretch of nine consecutive days playing, six of which will be at home against Miami and Milwaukee.