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8/2/2013 8:38 P.M. ET

Grossman impressing in second Majors stint

MINNEAPOLIS -- It's been a different Robbie Grossman in his second stint in the Majors.

Grossman was first with the Astros from April 24-May 27, and he hit .198 in 111 at-bats while primarily batting leadoff. He returned from Triple-A Oklahoma City on July 27, and entered Friday hitting .583 with two doubles and a homer since coming back up.

"It's definitely noticeable," Astros manager Bo Porter said about Grossman's improved play at the plate. "I said this before, even before Robbie was sent back to Oklahoma City, he had a good stretch where barreled the baseball, hit the ball hard."

The Astros sent Grossman to the Minors with instructions to not hit the ball in the air as much, which would encourage him to use his speed. It probably doesn't hurt that the outfielder is hitting ninth since his return.

"You look now, he's hitting line drives hard, hard ground balls," Porter said. "The one ball he hit in the air, he hit it out of the ballpark. It's definitely something he went to Oklahoma City to work on. He took to the plan. He worked on it, and he's definitely coming back here a lot more confident player, and it's showing with results."

Porter sticks to cautious approach with Altuve

MINNEAPOLIS -- The Astros continue to play it cautious with second baseman Jose Altuve, who was held out of the starting lineup for Friday's series opener against the Twins for the second game in a row with a sore left quadriceps muscle.

Altuve, hitting .284 with four homers, 34 RBIs and 26 stolen bases, was able to take batting practice and complete his normal drills, and he could have played, but manager Bo Porter and head athletic trainer Nate Lucero opted to rest him.

"It's one of those things, you don't want this to linger the rest of the season, and you want to go ahead and get it taken care of," Porter said. "Nate and I just leaned towards the side of getting it taken care of. He was able to get multiple days of rest, and once he gets back in the lineup, he can put it behind him."

One of the risks with putting Altuve into the lineup when he's not 100 percent is that he runs the risk of aggravating the injury.

"It's extremely hard," Porter said. "When you talk to Altuve, he's like, 'No, I can play, I can play, I can play.' He only knows one way to play, so it's not like you say, 'OK, look, be easy when you're on the bases.' He's just not that kind of guy that can hit a switch and play a different way. We kind of had to take it out of his hands."

Rookie Oberholtzer earns rotation spot

MINNEAPOLIS -- In a move that certainly came as no surprise, the Astros announced on Friday that left-hander Brett Oberholtzer would remain in the rotation for the foreseeable future. Oberholtzer was dazzling in his first Major League start Wednesday in Baltimore, throwing seven scoreless innings and allowing three hits.

The move means that Lucas Harrell will move back into the bullpen after making a spot start in place of Bud Norris on Tuesday in Baltimore. Harrell was in the rotation to start the year before being moved to the bullpen a month ago.

Oberholtzer will get the ball again on Monday against the Red Sox at Minute Maid Park.

"It was one of those things, each time [Oberholtzer] came up, he came up with the situation for us needing a long guy, and a couple of those times, he was able to get into the game, and it just so happened this time around, some guys had to get pushed back [in the rotation]," Astros manager Bo Porter said. "Obie went out and did a tremendous job and warranted us giving him another shot."

Oberholtzer, acquired a couple of years ago from the Braves in the Michael Bourn trade, said he's built to be a starter. He started 105 games in the Minor Leagues.

Porter opts for closer-by-committee with Veras gone

MINNEAPOLIS -- The Astros haven't had the need for a closer since trading Jose Veras to the Tigers on Monday. When that situation arises, manager Bo Porter said Chia-Jen Lo, Josh Zeid, Jose Cisnero and Josh Fields could each get a chance to close out games.

Porter said he'll handle the ninth inning based on matchups and prior usage of each pitcher.

"I'm going to try to keep all those guys fresh down there," he said.

Cisnero, a rookie, has gone 2-2 with a 2.59 ERA with 36 strikeouts in 31 1/3 innings since May 11, and he has taken on an increasingly important role in the bullpen. Fields (1-1, 6.23) is a Rule 5 pick who's yet to pitch in a save situation this year.

Both Lo and Zeid made their Major League debuts earlier this week. Lo was closing games at Double-A Corpus Christi and had six saves in 17 appearances between Corpus Christi, Class A Quad Cities and Class A Tri-Cities. Zeid had 13 saves at Triple-A Oklahoma City.

"It may be Fields one night, it may be Lo the next, it may be Ciserno," Porter said. "It all depends on usage moving forward and where we are in the lineup in that game."

Porter was asked if his closer-by-committee approach allowed him the freedom to use his most effective reliever prior to the ninth inning, instead of being married to the closer working the ninth, when the game might not have necessarily been on the line.

"Sometimes I think it can help" he said. "But I would love to have Mariano Rivera, and it doesn't matter who's coming up or what the situation is. If it's a save situation, I'm going to hand the ball to him and cross my legs and be ready to shake hands."

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.