The Mariners made seven roster moves before starting a homestand against St. Louis. The Mariners also placed right-hander Adrian Sampson on the 15-day disabled list and brought up left-handers Wade LeBlanc and David Rollins and right-hander Donn Roach from Tacoma. Seattle also transferred right-hander Tony Zych to the 60-day DL.
LeBlanc was set to start for Seattle on Friday night. It's his first start in the majors since 2014.
Aoki had started 67 games this season but was hitting just .245. He was demoted from the leadoff spot in the batting order recently and Seattle manager Scott Servais said he wanted Aoki to work on hitting against left-handers while in the minors. Aoki is hitting .177 against lefties this season.
Despite being a veteran, Aoki has not accrued enough service time in the majors to decline the minor league option. Because of that, he was easier for Seattle to send down in an attempt to address pitching concerns.
"We didn't have a lot of ways to go about this and fortunately he did have options left," Seattle manager Scott Servais said.
Sampson was placed on the disabled list with a right flexor bundle strain a day after he left Seattle's game in Detroit without throwing an official pitch. Sampson felt discomfort in his right elbow as he warmed up before the bottom of the first inning and was pulled.
Sampson getting pulled early strained Seattle's bullpen and required the moves with Rollins and Roach to add arms. Rollins is making his second stint with Seattle this season, while Roach has been a starter in the minors with Tacoma but is being brought up as a reliever.