The Mariners optioned Saucedo to Triple-A Tacoma on Thursday, Ryan Divish of The Seattle Times reports.
Saucedo is being sent down to make room on the active roster for Jose Castillo, who officially reported Thursday one day after being claimed off waivers. The left-handed Saucedo holds a 7.43 ERA and 12:6 K:BB over 13.1 innings for Seattle this season.