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09/05/12 7:53 PM ET

Late scratch causes Astros to shuffle lineup

PITTSBURGH -- As if trying to find a way to get 18 position players into the starting lineup wasn't a big enough chore for Astros interim manager Tony DeFrancesco, he was forced to rework his lineup about an hour before Wednesday's game when Fernando Martinez, who was originally in right field, was scratched with an inflamed boil on his left inner thigh.

DeFrancesco moved Jimmy Paredes to right field from left field, and J.D. Martinez was added to the lineup in left field in his first start since being recalled from Triple-A Oklahoma City. Earlier, DeFrancesco scratched third baseman Matt Dominguez's name from of the lineup after he injured his wrist in his final at-bat on Tuesday.

"It's been difficult," DeFrancesco said. "We've got a great group of guys here, and everybody wants to see if they belong in the Major Leagues and get an opportunity. There's a few guys you see in the lineup more often than others."

There has been speculation Major League Baseball could tweak the way it handles expanded rosters in the future by limiting teams to 30 players, only 25 of whom could be active for any game. The skipper wasn't so sure he'd like that.

"After managing winter ball last year with a 30-man rotating roster, every day you've got fresh arms in the bullpen," DeFrancesco said.

DeFrancesco has options with three catchers

PITTSBURGH -- With three catchers on his roster following the addition of Carlos Corporan, Astros interim manager Tony DeFrancesco plans to split playing time between Jason Castro, Chris Snyder and Corporan the best he sees fit.

"Three catchers is basically a luxury," he said. "You can pinch-hit late in the game and pinch-run. We're going to try to win as many games as we can, and if we have to get a catcher out of the game earlier, we can do that."

The only matchup DeFrancesco is committed to is having the veteran Snyder catch Lucas Harrell, who leads the team in wins and has been the most consistent starter. Castro figures to get the bulk of the playing time, but Corporan, a switch-hitter, did a nice job earlier in the year when he was called up by hitting .275 with three homers and nine RBIs.

"You saw him last year and saw the struggles he had adapting to Major League pitching," DeFrancesco said. "Down at the Triple-A level, the guy was filling in great, and when he was up earlier you noticed a big difference in his attitude with the way he's calling the game and his approach at the plate. A switch-hitting catcher is a manager's dream."

Wallace not an option at short for Astros

PITTSBURGH -- Injuries to Jed Lowrie, who hasn't played since July 14 with knee and nerve issues, and Marwin Gonzalez, who tore a ligament in his ankle last week, have left the Astros a little short-handed at shortstop, despite the expanded roster. The only true shortstop is starter Tyler Greene.

Astros interim manager Tony DeFrancesco said Matt Downs and even Jose Altuve could play shortstop in a pinch late in games, but don't expect to see Brett Wallace on the left side of the infield. Wallace played 10 games at shortstop for DeFrancesco this year at Triple-A Oklahoma City, but he's not prepared to put him there.

"He's proven himself as an everyday first baseman, and we're excited about the way he's coming along and the consistency of his at-bats," DeFrancesco said.

Greene has started 20 games for the Astros at shortstop since they acquired him in a trade with the Cardinals, including the last 13 in a row. Downs has appeared in only five games in the Major Leagues at shortstop, playing one inning there this year.

The Astros are hopeful Lowrie can get back on the field soon, beginning with a Minor League rehab assignment at Double-A Corpus Christi, which opened the playoffs Wednesday.

Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.