To make room on their 40-man roster, the Mariners designated right-handed pitcher Chris Heston for assignment. Heston gave up seven hits and seven runs (six earned) in three innings in a spot start for Seattle on Sunday against the White Sox. He had a 19.80 ERA in two appearances with the Mariners this year.
Aplin has hit .271 with a .369 on-base percentage, 30 home runs and 295 RBIs in 573 games over his six years in the Minors after being selected in the fifth round of the 2012 Draft out of Arizona State.
Heston, 29, was 2-1 with a 3.41 ERA in six starts for Triple-A Tacoma. He went 12-11 with a 3.95 ERA in 31 starts for the Giants in 2015 and threw a no-hitter that year, but he struggled with injuries and spent most of last season in Triple-A before being acquired by Seattle last offseason.
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB. This story was not subject to the approval of Major League Baseball or its clubs.