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8/8/2013 1:48 A.M. ET

Minor League affiliates sitting pretty in first place

HOUSTON -- The Astros' rebuilding process appears to be coming along nicely at the Minor League level, where the club's top six Minor League affiliates entered play Wednesday all in first place in their respective divisions.

The Astros' combined Minor League record of 376-271 (.581) is tops among all 30 organizations in baseball. Last year, the Astros had the top combined winning percentage among domestic Minor League clubs.

"I think it's a good indication of what's coming," general manager Jeff Luhnow said. "You look at those teams and there's prospects on every single team up and down the system. It's hard to have that much success in the Minor Leagues, but our coaches have done a terrific job. Scouts are doing a good job, but it's mostly the players. They're playing well."

Triple-A Oklahoma City (68-50) led the Pacific Coast League South division by four games, thanks to a 12-game winning streak. Double-A Corpus Christi and Class A Lancaster both won the first half titles in their leagues, but the Hooks (27-18) were tied for first place in the Texas League South and the JetHawks (28-17) had a 4 1/2-game lead in the Cal League South in the second half.

Meanwhile, Class A Quad Cities (27-16) had a half-game lead in the Midwest League's Western Division, while short-season Tri-City (29-21) had the same lead in the New York-Penn League's Stedler Division. Rookie league Greeneville (29-15) led the Appalachian League's Western Division by four games.

After two strong starts, Oberholtzer staying in rotation

HOUSTON -- With left-hander Brett Oberholtzer pitching so well in his spot start for Erik Bedard a week ago in Baltimore, the Astros are going to keep him in the rotation and employ a six-man rotation for the time being.

Oberholtzer, who's thrown seven scoreless innings in both of his Major League starts, is scheduled to pitch again Monday against the Rangers at Minute Maid Park. Jarred Cosart started Wednesday and will be followed Bedard, Brad Peacock and Dallas Keuchel.

"You look at all the work in which we've had in the bullpen, I think our starters give us the best chance to win," manager Bo Porter said. "Those guys now have an extra day. It allows us to put one of those guys in the bullpen during that extra day, and that helps. When we get ready to make a call to the bullpen, we have those guys available as well."

Cosart, who made his fifth career start Wednesday, became just the second pitcher in the last 100 years to go at least six innings and allow one or fewer earned runs in each of his first four starts. Bedard hasn't won since June 26, but he has a 3.97 ERA in his last six starts.

Peacock made his first start since being called back up Sunday in Minnesota, allowing three runs and four hits while striking out 10 batters in a career-high seven innings. Keuchel has pitched better as a starter than a reliever, going 5-4 with a 4.50 ERA in 14 starts.

Jordan Lyles has struggling lately, going 0-5 with an 8.49 ERA in his last eight starts. He hasn't won since June 18.

Arguing foul tip earns Porter first career ejection

HOUSTON -- Astros manager Bo Porter was ejected from a game for the first time in his career in the ninth inning of Wednesday's 7-5 loss to the Red Sox.

Porter was tossed by plate umpire Mark Carlson for arguing whether Red Sox catcher Jarrod Saltalamacchia had caught a foul tip off the bat of Astros catcher Jason Castro, who struck out to start the ninth. Castro argued the ball hit the ground before it hit the mitt and should have been a foul ball instead of a third strike.

Porter took up Castro's argument and became the first uniformed member of the Astros to get ejected this year.

"Whether it was a foul tip or not, realistically I don't know," Porter said. "I didn't even care to go look at it. The point I made to the umpire is that it's too big of a play, too big of a moment, not to check [with other umpires]."

Red Sox reliever Koji Uehara went on to work a 1-2-3 ninth for his 11th save in Boston's come-from-behind win.

De Leon called up while Cisnero sent to Triple-A

HOUSTON -- The Astros called up right-hander Jorge De Leon from Triple-A Oklahoma City on Wednesday and optioned right-hander Jose Cisnero to Triple-A. This will be De Leon's first time on a Major League roster.

In five appearances over 7 1/3 innings with the RedHawks, De Leon has notched one save, and allowed just six hits, only two walks and no runs. He threw 1 2/3 scoreless frames Monday vs. Colorado Springs.

The 25-year-old began the season at Double-A Corpus Christi, where he made 29 appearances (three starts, 4.27 ERA, six saves). Astros manager Bo Porter said De Leon came highly recommended from Triple-A manager Tony DeFrancesco.

"He said, 'Look, this guy's been throwing the mess out of the ball, a mid-90s fastball and a put-away slider,'" Porter said.

Cisnero went 2-2 with a 4.12 ERA in 28 games in relief for the Astros, allowing 49 hits and striking out 41 batters in 43 2/3 innings. Cisnero posted a 2.27 ERA in his first 18 games, but he had a 12.38 ERA in his last 14 games, allowing 13 hits and 10 walks in eight innings.

"He had a really good stretch where he was very effective and he struggled the last month and a half of the season, and it had a lot to do with mechanics," Porter said. "A lot of it had to do with fastball command. It looked like his confidence just continued to go down, and we just felt like with making the move, we could allow him to get down to Triple-A and get some things worked out and get his fastball command back."

In month-long funk, Carter held out of lineup

HOUSTON -- Astros outfielder/designated hitter Chris Carter was out of the starting lineup for the second consecutive game Wednesday as he continues to work through his slump. Entering Wednesday, he was in a 10-for-74 (.135) funk since July 4.

Manager Bo Porter said he and Carter had a good meeting Tuesday, and the skipper made him aware he was going to have a few days off, including Thursday's off-day.

"He's worked extremely hard in the cage, watching video with [hitting coach] John Mallee, and it was more like kind of take a break and take a step back and really evaluate things in which he was doing and also look at some of the things he wasn't doing well and why he was in the funk he's in," Porter said. "With the off-day, it almost gives him three days off and he'll be back in there on Friday."

Carter has proven to be a streaky hitter.

"I think our staff is figuring out ways to work with him and get him through the downswing more quickly," general manager Jeff Luhnow said. "We know what kind of power he has and game-changing bat he has. We just need to see it a little more consistently."

Hoes still getting acclimated to new club

HOUSTON -- Astros outfielder L.J. Hoes, acquired from the Orioles a week ago in the Bud Norris trade, had never stepped foot in Houston prior to Monday's series opener against the Red Sox. Needless to say, the trade has thrown his life upside down off the field.

"There's a lot going on, just like still trying to get out of my lease [in Baltimore] with my apartment I had and paying rent," he said. "The Orioles are supposed to reimburse me for that. I'm also trying to get all my stuff from over there, getting my car shipped out here. I have to sign new papers with my new team. There's a lot that goes into being traded. It has its ups and downs, but the ups outweigh the down."

Hoes said he'll probably spend the rest of the season in a hotel in Houston, which makes sense considering the amount of time he'll spend on the road with the club. He said his future plans depend on how the rest of the season goes.

"I don't know what the outlook is for next year, but I'll maybe try to find a place here and stay," he said. "Just have to go out there and not worry about all that stuff and get on the field."

Hoes, who grew up in Bowie, Md., as an Orioles fan, has taken notice of how oppressively hot it can get in Houston in the summer.

"I enjoy the hot weather," he said. "It may be a tad too hot, but it's better than the cold."

Worth noting

• Rookie shortstop Jonathan Villar underwent an MRI on Wednesday afternoon after suffering a left thumb sprain in Tuesday's game. The results weren't immediately available, but Luhnow expects him to miss a few days and perhaps be back in the lineup by this weekend.

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.