Mengden is expected to join the big-league rotation next week, likely starting Monday in Cleveland, the San Francisco Chronicle's Susan Slusser reports.
The team will decide Sunday whether or not to put Kendall Graveman (shoulder) on the DL, but that move seems highly likely, as he is expected to miss significant time with this latest shoulder injury. Mengden would be taking Graveman's spot in the rotation, but he could only be around for one start, as Jesse Hahn (triceps) could come off the DL next weekend. Mengden would be able to start Monday on an extra day of rest after tossing seven shutout innings in his last start Tuesday. He has a 2.21 ERA, 0.93 WHIP and 20 strikeouts in 20.1 innings this season at Triple-A.