The Pirates placed Stratton (knee) on the 60-day injured list Sunday.
Pittsburgh quickly moved Stratton off its 40-man roster after the reliever ruptured his left patella tendon during his appearance in Saturday's 10-2 loss to the Reds. Given the timing of his move to the 60-day IL, Stratton will miss the rest of the season, but the Pirates haven't indicated whether or not he'll require surgery. Pittsburgh selected lefty reliever Brady Feigl's contract from Triple-A Indianapolis to replace Stratton on the 40-man roster and 26-man active roster.