Manager Scott Servais said Zych (elbow) didn't feel 100 percent during his bullpen session Wednesday and may not return before the end of the season, Bob Dutton of The Tacoma News Tribune reports.
Zych was pushing to return from an elbow injury before the end of the season, but his chances are looking slim after reporting some soreness during Wednesday's bullpen. He compiled a healthy 2.66 ERA in 40.2 innings out of the Mariners' bullpen this season. Nick Vincent, Emilio Pagan and James Pazos will continue to serve as Seattle's primary setup men in his absence.