"He was good last year in [Class A] Lancaster," Astros general manager Jeff Luhnow said. "It's a little tough to gauge what performances are like in Lancaster, but reports were all excellent on him. He came into Spring Training and was one of the more impressive players in Spring Training. The times he came over from big league camp he did a tremendous job, and he's been lights out in the Texas League. This is a good time to challenge him."
McCullers isn't on the 40-man roster and this is his first experience at Triple-A, but Luhnow didn't rule out him helping Houston this year. The team would like to bolster the back of its rotation, where right-hander Brad Peacock (left intercostal strain) and left-hander Brett Oberholtzer (blister) are both in the disabled list.
"The reality is if he's pitching the way he's been pitching, we could probably benefit from having him here," Luhnow said. "There is a possibility he will be here."
McCullers is a hard thrower who has refined a third pitch -- a changeup -- which has boosted him. The Astros see him as a starter.
"We're very pleased with his repertoire right now, and we think it could play at a high level," Luhnow said.
Said Astros manager A.J. Hinch: "He's factoring in quickly."
Meanwhile, Fresno first baseman Jon Singleton has put himself on the radar to get called up after going 4-for-6 with a pair of homers, including a grand slam, and 10 RBIs in Fresno's 17-6 win Wednesday at Albuquerque. He leads all Minor Leaguers in homers (11) and RBIs (35). Houston isn't getting much production at first base from Chris Carter.
"We were hoping Jon would get hot and give us a reason to considering bringing him back to this team, and so those conversations are going to be had shortly," Luhnow said.
Hinch said Singleton is putting pressure on Carter and designated hitter Evan Gattis, who snapped an 0-for-19 streak Wednesday.
"It's at-bats that would have to be divvied up amongst them," he said. "The team doing well can mask some of it, but there's no doubt we're paying close attention."
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.