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03/21/11 6:45 PM ET

Brewers on lookout for pitching help

PHOENIX -- The Brewers are still leaning toward filling their fifth-starter void from within, but club officials are also keeping an eye on the waiver wire and trade market -- and on right-hander Shaun Marcum's stiff shoulder -- in case outside assistance becomes necessary.

The club's starting ranks are thin with Zack Greinke expected to miss at least one start and probably more with his cracked rib, prospect Mark Rogers working back from an early spring shoulder scare, left-hander Manny Parra slowed by a bad back and now Marcum missing one turn in the rotation to rest his stiff shoulder.

Marcum is scheduled to start again on March 26, and, for now, remains penciled in as the club's No. 2 starter. If he is healthy to begin the season, the Brewers only have one hole to fill, beginning on April 6 against the Braves.

"We probably will" fill from within, general manager Doug Melvin said Monday. "It's very difficult to make trades at this time of year because other teams are trying to preserve their depth. We're making a lot of calls."

The Brewers are not interested in left-hander Doug Davis, who threw for scouts on Monday, or in Oliver Perez, released by the Mets. They're also not in on free-agent right-hander Kevin Millwood, a Scott Boras client seeking a Major League contract and significant dollars.

Melvin would have liked to add some additional pitching depth before the start of Spring Training, but had trouble luring the sort of Minor League invitees the club hosted in the past. With the additions of Greinke and Marcum in trades, the Brewers' rotation was full, and the Dave Bush-types -- Bush was a former Brewers pitcher who signed a Minor League deal with the Rangers -- went to places where they perceived a better chance to make the team.

"We didn't get near the calls we did in the past," Melvin said.

Now that they have a need, part of the Brewers' issue is what to do with the fill-in when Greinke returns. That's why the waiver wire could be more helpful, assuming a team waives a player with Minor League options remaining in order to clear a 40-man roster spot.

The Brewers' own 40-man roster is full. That could be a complication even for an in-house pick, considering that of the four candidates mentioned by name Monday by manager Ron Roenicke -- Wily Peralta, Marco Estrada, Eulogio De La Cruz and Tim Dillard -- only Peralta is already on the roster.

Next up to audition as Greinke's fill-in is Estrada, scheduled to start Tuesday against the Padres at Maryvale Baseball Park.

Estrada will be on loan from Minor League camp and pitching in the spot occupied last week by Peralta, who will work a Minor League game instead. Peralta started Friday against the Rockies and recorded only one out while allowing five earned runs on five hits and two walks.

As Roenicke passed along a scouting report on Estrada, it was easy to connect the dots to Peralta.

"He's a strike-thrower," Roenicke said of Estrada. "He's not going to be intimidated [by] the situation of pitching in the big leagues. He's a guy that's done it, and that's really important.

"These guys that are starting these games, we're not expecting them to throw six shutout innings. They need to get us a good, quality outing, and I think some guys think, 'This is my one shot,' that, 'I've got to show them.' That's not really fair to put that on a guy."

Estrada made two spot starts for Milwaukee in 2010, and also pitched 15 games for the Nationals in 2008 and 2009.

Dillard and De La Cruz were to pitch against the Rangers on Monday, but that game was rained out. Their bids to be the fifth starter would have to wait.

"It's still open," Roenicke said.

Adam McCalvy is a reporter for MLB.com. Read his blog, Brew Beat, and follow him on Twitter at @AdamMcCalvy. This story was not subject to the approval of Major League Baseball or its clubs.