Seattle Mariners reliever Diego Castillo has been optioned to Triple-A Tacoma. Castillo has struggled, as have most of the Mariners, so this shouldn't come as too much of a shock. The 29-year-old right-hander posted a rough 6.23 ERA, 1.62 WHIP, and 7:7 K/BB ratio over 8 2/3 innings out of the bullpen so far this year. His services will likely be called upon again soon with the big league club so he shouldn't be in the minors for too long.