Manaea has been diagnosed with a right oblique strain and is expected to begin the season on the 15-day injured list, Anthony DiComo of MLB.com reports.
Manaea will be shut down for a couple weeks before being re-evaluated, but even in a best-case scenario he will not have time to be built back up for Opening Day. It's another blow to the Mets' starting pitching depth after it was revealed last week that Frankie Montas has a right lat strain. The club has been planning to deploy a six-man rotation early in the season, but it might now have to rethink that strategy.