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5/28/2013 9:10 A.M. ET

Astros recognize veterans on Memorial Day

HOUSTON -- As part of the Memorial Day festivities at Minute Maid Park on Monday afternoon, the Astros recognized veterans on the field from every conflict since World War II, including 90-year-old veteran Pat Duncan.

Duncan, who threw out the ceremonial first pitch, was a survivor of the Dec. 7, 1941, attack on Pearl Harbor while serving in the Navy and received eight commendations and medals in his career. The Astros and Rockies both wore commemorative camouflage hats and jerseys for the game.

"I think it's tremendous," manager Bo Porter said. "When you think about our country and all the things which we've been though, to be able to have a day where the entire league honors the veterans and what it is our country stands for, it's great for baseball and great for our country."

Memorial Day is certainly special to Astros outfielder Robbie Grossman, whose father, Rob, spent 11 years in the Navy and was an aviator in the first Gulf War. He was a Seahawk pilot who flew helicopters off the back of frigates, cruisers and destroyers.

"It's a tribute to the people who served this country and fought for our freedoms and everything we have and take for granted," Grossman said. "It means a lot to me."

Astros option outfielder Grossman to Triple-A

HOUSTON -- Two weeks after Astros manager Bo Porter said Robbie Grossman would get every chance to prove he was his starting center fielder, the team optioned the outfielder to Triple-A Oklahoma City following Monday's 3-2 win over the Rockies.

Grossman, who was called up April 24, went 0-for-5 with a walk and three strikeouts on Monday to drop his batting average to .198 and on-base percentage to .310. He started 26 of 28 games, mostly in the leadoff spot.

"Just part of the game, part of the business," Grossman said as he left Minute Maid Park. "If I played better it wouldn't matter, but it is what it is."

The club will call up right-hander Brad Peacock from Triple-A on Tuesday, providing the staff with an extra pitcher heading into Coors Field later this week.

Grossman was acquired by the Astros in last year's trade that sent pitcher Wandy Rodriguez to the Pirates. A Houston-area native, he hit .324 with a .452 on-base percentage in 19 games for Oklahoma City before being called up.

"They said to go down there and keep playing hard," Grossman said.

The move could open the door for Brandon Barnes, who won Monday's game with a walk-off win in the 12th inning, to get more playing time. Center fielder Justin Maxwell, who fractured his hand last month, could return soon and will begin a rehab later this week.

Singleton set to begin campaign in Minors

HOUSTON -- Astros top prospect Jonathan Singleton will begin his season Tuesday for Class A Quad Cities against Kane County after missing the first 50 games of the season for violating the Minor League Drug Prevention and Treatment Program for a drug of abuse -- his second positive test.

General manager Jeff Luhnow said the plan is for Singleton to spend a few days with Quad Cities and a few days at Double-A Corpus Christi before eventually winding up with Triple-A Oklahoma City. Singleton has spent the season so far playing in extended spring.

"We have him on a schedule, and it partially depends on when the team is at home and when the team is on the road and what kind of trip it is and all that," Luhnow said. "We'll obviously monitor him and all that. It's different than coming back from a medical situation when you have to get daily checkups to make sure he's OK. We know he's OK. He's been playing in Florida."

Singleton, a left-handed-hitting first baseman, hit .284 with 21 homers and 79 RBIs in 131 games last year with Corpus Christi and was expected to push for playing time on the Major League club this year. The Astros acquired Singleton and three other players from the Phillies in the Hunter Pence trade in 2011.

When asked if Singleton could reach the Majors this year, Luhnow cautioned that he had yet to even play at Triple-A.

"I never assume someone is going to make that jump successfully out of the gate," Luhnow said. "Ultimately he will, but he's got to demonstrate to us he can handle that environment and pitching before we move him up here."

Porter gives Harrell words of encouragement

HOUSTON -- Prior to the Astros' game on Sunday against the A's, manager Bo Porter told pitcher Lucas Harrell to come and visit him in the dugout early in the game for a heart-to-heart talk. Harrell was coming off a frustrating outing in which he couldn't escape the second inning, and the first-year skipper wanted to provide words of encouragement.

"It wasn't anything specific," Porter said. "It has more to do with the maturity level it takes to play at this here level and understand that things aren't always going to go the way you want them to go. You find out more about yourself when times are hard than you do when everything goes well."

Harrell was clearly frustrated when the left the game, and Porter said he talked to the right-hander about channeling his emotions.

"I was just explaining to him he has tremendous talent and an opportunity to be an elite starter in this league, but controlling your emotions and understanding taking care of things you have control over will go a long way in determining whether or not you're going to reach your potential," Porter said. "I told him, 'As your manager, my No. 1 job is to do everything I can to help you play to your potential, and if I see you doing something that's not going to allow you to do that, I'm going to advise you accordingly.'

"It was a great conversation, and he understood exactly where I was coming from. Like I told him, 'I'm here to help you. I'm on your side and we're on the same team. If I see something I can believe can help you, it's my job to bring it to your attention.'"

Porter said talking to a player during the game can make the player feel more at ease.

"If you get a natural setting, it lessens the heightened intensity of the situation, and I found those conversations are a little bit more receptive and better conversations than if you set it in a closed-door room," he said.

Carter given day off; Crowe gets nod in center

HOUSTON -- Chris Carter, who went 1-for-11 in the three-game series against Oakland, was out of the starting lineup Monday, but manager Bo Porter said it had more to do with trying to give Trevor Crowe another chance to start in center field.

"He played really well [Sunday], and we have a lefty going tomorrow [Colorado's Jorge De La Rosa], so it will be a dominant right-handed lineup. So we had Crowe in there today," Porter said.

Carter leads the Majors with 74 strikeouts in 169 at-bats and hasn't homered since May 12, but Porter said that's part of the growing pains of a young hitter.

"He's figuring out himself and the league and what they're trying to do to him," he said. "We know the power potential is there. You do want more consistent contact as time goes on, and Chris is going to get all those things figured out and we're going to be patient and allow him to figure those things out."

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.