"Shoulders can heal quickly," Mets assistant general manager John Ricco said. "They can take time. Clearly, he's not ready yet, so we'll give it more time, rehab and see where it goes."
Despite the diagnosis, surgery is not currently an option for d'Arnaud. The Mets will first see how his shoulder heals.
In the interim, Kevin Plawecki will continue to start most days at catcher for the Mets, with Rene Rivera serving as a backup. Plawecki has recently warmed at the plate after a slow start, batting .400 with three doubles during the Mets' four-game series in San Diego.
Continued success could give Plawecki a chance to eat into d'Arnaud's playing time after the latter returns. In addition to struggling defensively prior to landing on the disabled list, d'Arnaud was batting just .196 with no home runs in 52 plate appearances.
• Second baseman Neil Walker could be out until Wednesday with a badly bruised right shin. Mets manager Terry Collins said that Walker, who was limited to a pinch-hit appearance Sunday in San Diego, is unlikely to return until that time.
• Reliever Josh Edgin's Minor League rehab stint officially came to an end on Monday. The Mets plan to option Edgin, who is recovering from March 2015 Tommy John surgery, to Triple-A Las Vegas.
Anthony DiComo has covered the Mets for MLB.com since 2008. Follow him on Twitter @AnthonyDiComo and Facebook, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.