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7/2/2013 8:40 P.M. ET

Two Astros prospects make Triple-A All-Star Game

HOUSTON -- The Astros organization already has three players going to the Futures Game during All-Star Weekend, so what's two more Triple-A All-Stars?

Oklahoma City pitchers Jarred Cosart and Jason Stoffel were named Pacific Coast League All-Stars on Tuesday, and they will compete in the 2013 Dolan Auto Group Triple-A All-Star Game in Reno, Nev., on July 17.

The pitchers are among 30 players on the PCL roster who will take on the International League All-Stars.

"The talent in our system continues to filter through to every level, where you can point to a handful of guys that you can imagine playing and having an impact in the Major Leagues," Astros general manager Jeff Luhnow said. "That's the way it's supposed to be, and these selections reinforce our belief in the quality of players we have."

Cosart, the club's No. 4 prospect according to MLB.com, was one of 13 players on the squad who were picked by managers, media members and online fan voting. He's got the third-best ERA in the league (2.98), the second-lowest opponent batting average (.205) and the fourth-highest strikeout total (90).

"Cosart is one of the top pitching prospects in baseball, and he's been consistently going out there and delivering good start after good start with dominating stuff," Luhnow said. "He's the type of guy whose success will translate pretty quick to the big leagues when he gets a chance to come up here.

"He's not a complete finished product yet, but he's getting closer every day. The selection is well deserved."

In 17 games -- 16 as a starter -- Cosart has paced the Redhawks with seven wins, 87 2/3 innings of work and 9.32 strikeouts per nine innings.

Stoffel is a reliever, and he was one of 17 players on the All-Star roster who were selected by the PCL office. The righty has a 1.89 ERA in 23 outings, striking out 27 in 33 1/3 innings and never allowing multiple runs in an appearance.

"He's a prospect we've been high on for a while," Luhnow said. "He has the stuff to put big league hitters away. We expect to see him in the bullpen up here next year."

It marks a second consecutive All-Star trip for the duo, as both were named Texas League Mid-Season All-Stars last year while pitching for Double-A Corpus Christi.

The Triple-A All-Star Game will be broadcast live on MLB Network, the American Forces Network and the Triple-A All-Star Game Radio Network at 8:05 p.m. CT on Wednesday, July 17.

Astros option Ambriz, call up long reliever Oberholtzer

HOUSTON -- The Astros optioned relief pitcher Hector Ambriz to Triple-A Oklahoma City on Tuesday and called up Brett Oberholtzer in his place.

Ambriz struggled mightily in the last four weeks, giving up seven runs and 15 hits over his last 6 2/3 innings of work. He finished his stint in Houston with a forgettable performance Monday night, allowing three runs on four hits in one inning of work during a 12-0 loss to the Rays.

"Quite frankly, our feeling was Ambriz needed a break," Astros general manager Jeff Luhnow said. "He's a good Major League pitcher who's not had a lot of success the last couple of weeks. We feel like there's probably a few things he needs to work on down there to get back in a groove so he can help us later this year."

Oberholtzer was a starter for the Redhawks, posting a 4.60 ERA and 5-6 record in 15 starts. It is his second time with the Astros this year. He gave up two solo homers to the Indians on April 21 in a relief appearance.

Manager Bo Porter and Luhnow said Oberholtzer would most likely see work as a long reliever, possibly as soon as Tuesday night's game against Tampa Bay.

"We wanted to get somebody down in the 'pen with starting ability and could give us length now that [Jose] Cisnero has been pitching more on the back end," Porter said. "The move just made sense given the available innings we had down in the bullpen."

Ambriz has appeared in 39 games for the Astros this year, tallying a 5.40 ERA and two saves as a late-inning mainstay.

Astros set Minors debut for No. 1 Draft pick Appel

HOUSTON -- In a quick turn of events, inquiring minds will not have to wait long to see No. 1 overall Draft pick Mark Appel pitch at the professional level.

Appel, who agreed to a contract with Houston two weeks ago, will make his first pro start Friday with Class-A Tri-City. On Tuesday, he was working out at the Astros Spring Training facility in Kissimmee, Fla., and he will report to the club Thursday.

For a top selection, Appel has moved through the post-Draft process with efficiency. The Houston native agreed to terms, including a $6.35 million signing bonus, just 12 days after being drafted and will be on a roster by Independence Day.

General manager Jeff Luhnow said the organization had an approximate timetable for Appel's starts.

"We're not going to set any schedule on him, but we will assess him after every game," Luhnow said. "We don't want to create too many set expectations for Mark."

Appel will be on a strict pitch count, but Luhnow and the organization continue to decline revealing what that number is or how many innings the former Stanford standout can pitch.

Luhnow has previously said he expects Appel to make multiple stops at the Minor League level this summer while not ruling out a spot for him on the Houston roster to begin next season.

"I would never put limitations on a player with his talent," Luhnow said. "We will know the answer when the time comes. All indications are that he's a player who could move very quickly through the Minor Leagues."

Pena returns to Astros after death in family

HOUSTON -- Astros first baseman Carlos Pena made it back for Tuesday's game, but only barely.

After missing two days because of a death in the family, Pena arrived to Minute Maid Park approximately two hours before first pitch and was unable to warm up with the team.

He was not in the starting lineup, but manager Bo Porter said Pena would be available off the bench despite the late arrival.

"I got a text from him, and he's on his way, trying to get here," Porter said just before the Astros took batting practice. "We want him back."

Without Pena, one of the team's best power bats, Houston continued a woeful offensive stretch by scoring only one run and seven hits combined in two losses.

Despite the poor outings, Porter said he told Pena not to rush anything.

"I actually told him to take his time," Porter said. "You can plan on being there for a certain number of days, but then you can get there and the family can be in a different condition. I told him to take care of his family. It's a very trying time for his wife and his family."

Pena has eight home runs and 25 RBIs to go along with a .221 average this season. Chris Carter took Pena's place at first base Monday and Tuesday, with Brett Wallace starting there Sunday.

Chris Abshire is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.