• Singleton isn't the only notable recent addition to the Corpus Christi roster, as center fielder Justin Maxwell began a rehab assignment Tuesday with the team.
"I'm pretty excited about the lineup right now in Corpus Christi," Luhnow said. "You've got a lot of thunder in that lineup between [George] Springer, Maxwell, Singleton and [Domingo] Santana hitting together."
Maxwell, who went 0-for-3 with a run scored, is returning from a fracture to his left hand that he suffered on April 24 and put him on the disabled list.
Porter said he and team doctors will be evaluating Maxwell's ability to play consistently without pain.
"For me, it's more about the health on consecutive days," Porter said. "Yeah, you might be able to swing the bat well one day, but I want to know how it feels the next day and then after three to four days in a row. That's more of a parameter for evaluating him than his performance."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. Chris Abshire is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.