Armstrong was optioned back to Triple-A Columbus on Monday.
Already in his second stint with the Indians this season, Armstrong allowed just one walk and struck out three while tossing 2.2 scoreless innings of relief before being sent back to Columbus. The 26-year-old now owns a 5.62 ERA through eight innings (five appearances) with the Indians this season, though all five runs he gave up came in one outing. Armstrong will likely see another chance with the big-league bullpen in 2017, but most of his innings should continue to come in low-leverage situations. The move clears room on the roster for the hot-hitting Yandy Diaz, who was recently recalled from Triple-A.