MILWAUKEE -- The Pirates can begin making September callups Wednesday, but do not expect those until after Class AAA Indianapolis' season ends Labor Day, and do not expect many.

That was the word from general manager Neal Huntington Friday: He described the Pirates as "likely" to wait until after the top affiliate's final game, a Sept. 6 matinee, and he described the number he projects to recall as "moderate."

The dominant factor in every set of callups is the 40-man roster, which currently is full but has room to give, including the possible shifting of pitcher Ross Ohlendorf from the 15-day disabled list to the 60-day.

The most likely players on the 40-man roster to be recalled are two recent trade acquisitions, outfielder John Bowker and pitcher Joe Martinez. Huntington said when they were acquired July 31 he expected them to be callups. Also in this category are pitcher Brad Lincoln, catcher Jason Jaramillo and, to a lesser extent, shortstop Pedro Ciriaco.

Pitchers Charlie Morton and Brian Burres should be added, too, with Burres currently on the 25-man roster on a temporary basis and Morton looking like the starter Sunday to take Ohlendorf's turn. Manager John Russell said an announcement on the latter should come today.

The only player not on the 40-man likely to get consideration for a callup is outfielder Brandon Moss, who has batted .261 with 20 home runs and 84 RBIs while spending all season with Indianapolis.

Moss told Indianapolis broadcaster Scott McCauley in an interview Friday that he does not expect to get the call.

"The Pirates have guys they envision being there a while, and I don't think I'm a callup guy because there is no room to play me," Moss said. "I'm pretty sure they don't want to call a guy up to sit and get paid."

He added, "Will I re-sign with the Pirates if I don't get called up? Who knows? That will be a decision I make with my agent and my family."

Third baseman Pedro Alvarez was out of the lineup Friday after a 2-for-27 slump, part of a hot-and-cold pattern prevalent since his arrival.

"I do sometimes have stretches where I do pretty well, stretches where I struggle," Alvarez said Friday. "Those are things they say you've got to learn from. I feel like I'm trying to make the proper adjustments, working to find that middle ground."

The key to snapping out of slumps, he added, usually has less to do with mechanics than with mindset: "Keep it simple. It always seems to click when I keep it simple. I usually don't think it's something with my swing. It's usually something the pitcher is doing to adjust to me, and I've got to adjust back."

• Alvarez's place was taken by Andy LaRoche, his first start since Aug. 10. Trying to involve LaRoche, Russell said, was his primary motivation for the move. He acknowledged that part of the reason LaRoche has struggled immensely in a bench role -- 11 for 77 for a .143 average in his past 44 appearances -- is playing sparingly. "The job is tough enough," Russell said of pinch-hitting. LaRoche went 0 for 3 Friday.

• Jeff Karstens, scratched from his start Wednesday because of arm fatigue, threw a light side session and remains on track to pitch Tuesday in Chicago.

• Russell, on Washington phenom Stephen Strasburg likely needing Tommy John surgery: "You never know. You try to protect guys as best you can, but there are things that are unforeseen. The preventive things that everyone does right now are much better, but injuries will happen. It's unfortunate."

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