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5/31/2013 1:37 A.M. ET

Martinez rewards Porter's faith after rough game

DENVER -- After outfielder J.D. Martinez went 0-for-5 with five strikeouts in Monday's win over the Rockies, Astros manager Bo Porter tapped him on the back and told him he would be right back in the lineup the next day. Martinez went 8-for-13 in the following three games against Colorado, rewarding Porter's faith in him.

"I told him he's not going to go the rest of the season and not strike out five times, so why does it matter if it happened in five consecutive at-bats?" Porter said. "You can't let it become a mental thing, where you're thinking about the strikeout. You have to make sure you stay in the frame of mind that gives you the best opportunity to be successful."

Martinez went 4-for-5 on Thursday's win over the Rockies, setting a career high for hits. He's hitting .416 (15-for-36) over his last eight games, with three doubles, two home runs, eight RBIs and six runs scored. Martinez drove an RBI single up the middle in the eighth inning Wednesday to break a 2-2 tie.

"It goes back to him using the whole field," Porter said. "J.D. has done a great job using the whole field, driving the ball the other way and taking what the opposition is giving him. That was a tough pitch last night, and if he would have tried to pull that ball, it's a ground ball to the shortstop and the inning is over. He stays in the middle of the field and kept his nose down and drove the ball up the middle."

Luhnow happy with Cosart's progress in Triple-A

DENVER -- Astros general manager Jeff Luhnow said Thursday he believes top pitching prospect Jarred Cosart is close to being ready for the big leagues, but there's no need to for starting pitching considering how well Houston's starters have performed lately.

Cosart, who just turned 23, is 5-2 with a 2.65 ERA in 54 1/3 innings for Triple-A Oklahoma City, with 57 strikeouts and 29 walks.

"Jarred Cosart is a starting pitcher in our organization, and we don't have a spot in our starting rotation," Luhnow said. "Will that change later on this summer? Maybe. Is Jarred ready to be in the big league rotation right now? I don't know the answer to that. I think he's close. There are some things we want him to improve on.

"He is improving and working on it, and the pitching coaches are working with him. He's demonstrated so far this year the ability to succeed at the Triple-A level, which is great. As we've seen numerous times, success in the Minors doesn't always translate to success in the big leagues. There's no real rush, and we want him to be comfortable and make sure he's in the position he has the highest chances of succeeding."

Luhnow, who didn't rule out seeing Cosart at some point this year, was asked if the Astros were taking his arbitration clock into consideration.

"Our primary consideration is bringing him up when his development is done in the Minor Leagues and his development can be continued most effectively at the big league level," he said. "We don't feel he's there yet. It's not an issue of clocks, because the reality is a lot of players -- even when they come up for the first time -- they may not stick and will go back and forth. We're not trying to be too smart about it. When he's ready, we'll know, and if there's an opportunity, he'll come up."

Worth noting

• Closer Jose Veras was given Thursday off after throwing three days in a row, meaning right-hander Hector Ambriz was in line to close for the Astros.

• Right-hander Edgar Gonzalez is dealing with shoulder soreness and was unavailable Thursday. Porter said the discomfort stemmed from fatigue.

• Shortstop Marwin Gonzalez continues to deal with a slight strain of his right hamstring and remained out of the lineup Thursday, though he was available off the bench.

• Porter said the Astros will likely go back to seven relief pitchers in the next few days. The team has been carrying eight relief pitchers since Brad Peacock was called up earlier this week.

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.