President of baseball operations David Stearns said Saturday that Blackburn has a spinal fluid leak in his back, Tim Britton of The Athletic reports.
The Mets aren't sure exactly how Blackburn suffered the injury, but the team is shutting him down for the time being. Stearns noted that the right-hander's injury isn't expected to be a long-term issue, though there's no telling how long he will be held out.