Maine will now be shut down for roughly a week before being reevaluated.
Maine, on the disabled list since June 11 with a pinched nerve in his right shoulder, felt the same kind of pain that initially caused him to go on the DL while he was playing catch on Thursday.
"I was down in Florida, and everything felt fine," Maine said. "I came up here and I got through Monday and got through my bullpen [session], but yesterday it just came back. I couldn't go out and pitch like that. I couldn't go out and hurt myself even more or just go out and pitch at 60 or 70 percent. That's not going to do the team any good."
Maine pitched four innings in a rehab start for Class A St. Lucie on Monday, allowing one run while throwing 60 pitches. After his bullpen session on Wednesday, Maine talked of feeling shoulder "achiness," which he was quick to differentiate from pain.
That distinction changed on Thursday.
"It's hard to judge just how much it's hurting," Maine said. "I thought I could throw through that, but I couldn't."
Maine and Mets general manager Omar Minaya reiterated that there does not appear to be anything structurally wrong with Maine's shoulder, which was surgically repaired last Sept. 30. Maine had an MRI performed on the shoulder just before he was placed on the disabled list, and additional tests since then have not revealed anything more serious.
Maine did receive a cortisone shot in the shoulder on Thursday and hopes to be able to make a quick return once he starts throwing again.
"I don't think I'll be starting from scratch," Maine said. "I'll probably be able to start with 50 or 60 pitches and work my way up to 80, like I was supposed to Saturday."
Even so, the Mets do not expect Maine to return until after the All-Star break. Fortunately for them, Maine's replacement in the rotation, Fernando Nieve, has won all three of his starts and has a 1.31 ERA.
Tim Britton is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.