The Mets on Thursday gave Marcum a diagnosis of nerve inflammation in his neck, administering trigger-point injections to relieve his discomfort. They will re-evaluate him in Florida this weekend, but that does not necessarily mean a return to the mound.
Even once Marcum does begin pitching, he must build his arm strength back to Major League levels. Because the right-hander has not even completed a bullpen session over the last two weeks, that could take significant time.
"It's all about being able to get his arm up to a consistent release point," Collins said. "If the nerves are flaring up again, he's going to have a tough time doing it, which is going to cause some discomfort. Until a few days from now, we're not really sure where we're at."
In the interim, Aaron Laffey will pitch Sunday, with a chance to stick in the rotation depending on his performance.
Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.