Guerra, the Brewers' best starting pitcher before elbow inflammation sidelined him earlier this month, tentatively is scheduled to start Saturday for Triple-A Colorado Springs at Oklahoma City, manager Craig Counsell said. The destinations and timetables for Middlebrooks and Barnes were still under discussion.
"Everything went perfect. The three guys involved all did good. No problems," Counsell said. "The next step is minor league games for all of them. Will will probably get the head start on them because he's ready to go after this."
Unless a need arises before Sept. 1, the Brewers are likely to wait until after rosters expand to reinstate those players from the DL.
Counsell, GM David Stearns and assistant GM Matt Arnold will discuss other September callups during this homestand, Stearns said.
"I imagine what we'll do is we'll have some callups on the first and some callups at the conclusion of the Triple-A season [on Sept. 5]," Stearns said. "But we can keep a pretty fluid process and decide on what we need as we get closer."
Asked about his philosophy toward callups, Stearns said, "In general, I would tend to err on the side of fewer than more. I'm probably not unique in that opinion. You have 25 guys all year. Major League clubhouses are generally made for 25 guys. So in general, if guys are going to be here, we want them to have a purpose."
One candidate for a callup, Triple-A outfielder Lewis Brinson, was reinstated from the disabled list on Tuesday after recovering from a mild hamstring strain. The Brewers acquired him from the Rangers in the Jonathan Lucroy trade, and will have to add Brinson to the 40-man roster by November's deadline to protect players from the Rule 5 Draft.
Adam McCalvy has covered the Brewers for MLB.com since 2001. Follow him on Twitter @AdamMcCalvy, like him on Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.