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5/15/2013 8:48 P.M. ET

Norris' Sunday start still up in the air

DETROIT -- Two days after tweaking his back throwing warmup pitches prior to the sixth inning of his start in Monday's 7-2 loss to Detroit, Astros starter Bud Norris' status is still in question for Sunday's series finale against the Pirates.

It's not completely unexpected, as back injuries -- he was officially diagnosed with lower back spasms -- tend to linger for a few days before improving.

Manager Bo Porter said on Wednesday he's going to continue to take a wait-and-see approach, with the hope that Norris can indeed take the hill in Pittsburgh. However, Porter's also not going to risk a slight, nagging injury turn into an extended absence.

"I talked to the trainers and backs can be tricky," Porter said. "We'll weigh all those options and make the best decision long term, because this is one start, and we don't want this to linger through the course of the year. We want to be very cognizant and make sure we're doing something that's going to affect him long term."

Porter said Norris' status would be determined "in the next couple days."

Reliever Josh Fields, meanwhile, continued his rehab assignment at Class A Quad Cities. The right-hander made two appearances recording two outs before suffering a strained right forearm. He's thrown four innings, yielding two hits and striking out four for the River Bandits.

"We'll have to make a decision when he's ready to go from a physical standpoint," said Porter.

Justin Maxwell, who stayed in Houston for treatment on his fractured left hand during the six-game road trip, has begun lightly swinging a fungo bat, Porter said.

J.D. showing he belongs in Astros' lineup

DETROIT -- It's only been two days since manager Bo Porter named J.D. Martinez as one of his three everyday outfielders. Already, the Astros are beginning to see the benefits of the move.

The 25-year-old had four hits in the previous two games entering Wednesday's series finale in Detroit. Three of those hits were doubles, all off a pair of the American League's most talented pitchers in Anibal Sanchez and Doug Fister. On Wednesday, he hit a three-run homer off Tigers right-hander Max Scherzer.

Martinez said knowing he's in the lineup, no matter his performance in the previous game, has made a world of difference.

"Absolutely. That plays a huge role," he said. "It always seems like, at least a lot of the time, it's been where if you have a bad game, you don't know if you're going to be in there tomorrow. It's a relief not to have to worry about that as much."

After posting an 0-for-3 against the Angels on Thursday, Martinez saw his average fall to .218 and was benched for the following two games against Texas. He started the series finale Sunday, but went 0-for-4.

With consistent time in the lineup, Martinez feels he's beginning to see pitches better. That was most evident during an 11-pitch at-bat against Fister in the second inning on Tuesday. He battled Fister before poking a two-run double down the left-field line on a 77-mph curveball.

At-bats such as those are the ones Porter believes Martinez is regularly capable of.

"He's one of those guys that when he gets going, he can get going. He's a run producer," Porter said, "and again, that's led to the decision of giving him an opportunity to play every day. We believe he's a guy that can be a middle-of-the-order run producer, and we'll see where it goes."

Harrell's opinions elicit counsel from Porter

DETROIT -- Defensively, the Astros are constantly shifting their positioning in the field with each batter. To this point, it's carried them to the Major League lead in double plays turned (53). It's also, at times, cost them.

Houston pitcher Lucas Harrell felt Tuesday night's 6-2 loss to Detroit, in which he cruised through 4 2/3 innings while yielding one hit and two walks, was one of those times. A three-run fifth inning, which abruptly turned a two-run Astros' lead to a deficit, left Harrell believing a few of the four straight hits allowed were playable without a shift -- specifically a double to left by No. 9 hitter Ramon Santiago.

"I felt like I was good all game," he said Tuesday. "I felt like the pitch to Santiago -- and those guys hit -- I felt like those were balls that, I don't want to say should've been caught, but I felt like that could've been close to being caught. It's not [left fielder] J.D. [Martinez's] fault, but it's just kind of how things worked out."

Prior to Wednesday's series finale in Detroit, manager Bo Porter addressed Harrell's comments. The skipper said he hadn't heard what Harrell said until arriving at the ballpark, and while Porter doesn't take issue with any player expressing his opinion, he didn't believe Harrell used the proper forum in doing so.

"I took the opportunity to talk to Lucas this morning, and I explained to him pretty much my thought process on his comments," Porter said. "I said to him, 'Listen, if you have something to say and you want to voice your opinion, I have a complete open-door policy and we all know that. Come in here, say what's on your mind, you will never get a problem out of me.'

"I will say this. You look at the shift defense and how we're defending teams, I think we're up at the top of the league in double plays turned. I know for sure that if we're just playing traditional defense where everybody believes defenders should play, we wouldn't be at the top … you have to be able to take the good that comes with it and sometimes the bad."

Porter referenced a play by third baseman Matt Dominguez in the first inning. Dominguez had been lined up almost as the shortstop, with the result being an inning-ending double play.

"If Matt Dominguez's playing where a third baseman should be at, that's a base hit to left field," Porter said. "Instead of a base hit, it's a ground-ball double play. Lucas Harrell smiles coming off the field, 'Great job.' How can that be a great job, but then something else that don't get fielded is a bad job. You can't get the best of both worlds."

Anthony Odoardi is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.