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8/6/2014 10:47 P.M. ET

Luhnow has eye on waiver wire for possible trades

PHILADELPHIA -- Astros general manager Jeff Luhnow is keeping a close eye on the waiver wire these days, and won't rule out any further trades. The Astros traded left-hander Wesley Wright to the Rays last August in exchange for cash considerations after he was claimed off waivers.

Now that the non-waiver Trade Deadline has passed, deals involving players on the 40-man roster cannot be made unless the players already have cleared waivers. In other words, the player must be offered to the other teams in reverse order of the standings, and if he is claimed by one of those teams, he cannot be traded. The club that placed the player on waivers can either withdraw the request and keep the player, or trade the player go to the claiming team, which would then have the rights to the player.

Teams will often put many, if not all, of their players on waivers to gauge which teams might be interested in a trade, and the Astros are no different.

"We're always looking at every player that's put on waivers and will make a determination whether or not it's worth us making a claim based on how realistic it really is and whether or not we have a spot or a budget to absorb that player," Luhnow said. "We're going to continue to do that, and I expect if we put our guys on waivers, most of them will get claimed because they're young and affordable, but we're not looking to do anything.

"You go through the process anyway because you never know. Last year, we ended up moving Wesley through that, but we don't anticipate anything this year."

Springer has setback with quad in rehab game

PHILADELPHIA -- Astros rookie outfielder George Springer suffered a setback Wednesday during his Minor League rehab assignment at Class A Quad Cities, leaving the game in the fifth inning after he tweaked a strained left quad that's kept him on the disabled since July 20.

The Astros were hoping to activate Springer on Thursday against the Phillies or when the team returns home Friday against the Rangers. Springer will fly to Houston to be re-evaluated, Astros manager Bo Porter said.

"He hit a double and felt it a little bit in his quad and for precautionary reasons we went ahead and pulled him out of the game," Porter said after his team's 10-3 loss.

Springer, playing in his third rehab game, doubled in the first inning and walked in the fourth while starting at designed hitter against Burlington. He was lifted for a pinch-hitter in the fifth inning. Porter said earlier in the day Springer was scheduled to play seven innings in the field, so it's unclear why he was at DH.

"We're all behind him and we want the best for him," said Astros first baseman Jon Singleton, who, like Springer, made a much-anticipated debut this year. "If he doesn't come back, we'll make the most of it. We're definitely hoping he makes it through."

Springer started in right field for the first time Tuesday for Quad Cities and was 0-for-2 after serving as designated hitter on Monday in his first rehab game.

"We'll have a good indication of how he recovered from back to back days [in the field] and we'll be able to make a decision from there," Porter said prior to Wednesday's game. "Maybe we'll have him off Thursday and have him ready to go on Friday."

Springer was hitting .231 with 20 homers and 51 RBIs in 78 games since being called up in the middle of April. He was the American League Rookie of the Month in May.

Fowler nearing start of rehab assignment

PHILADELPHIA -- Astros outfielder Dexter Fowler, who has missed 34 games with a strained intercostal, said Wednesday he could begin a Minor League rehab assignment within the next week, barring any setbacks.

He's been hitting off a tee and was scheduled to take batting practice on the field prior to Wednesday's game, but the Astros hit inside instead after playing 15 innings on Tuesday night. Fowler should hit on the field Thursday for the first time since going on the disabled list June 27.

"I'm feeling a lot better," he said. "I've been anxious since the first day."

Fowler, like fellow injured outfielder George Springer, would likely need at least three games in the Minor Leagues before being activated -- one at designated hitter and two in the field.

Astros manager Bo Porter said injured outfielder Alex Presley, who's been out for a month with an oblique strain, is also getting close to a rehab stint.

"It will be good to get those guys back," he said.

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.