Heston was designated for assignment Wednesday, Ryan Divish of The Seattle Times reports.

EDGE Analysis

The Mariners landed outfielder Andrew Alpin from the Astros on Wednesday, so in order to place him on the 40-man roster, someone needed to get the boot. Heston was ultimately the odd-man out after struggling significantly in the big leagues, so he'll work on regaining his confidence in a starting role with Triple-A Tacoma as an organizational depth piece.