Dr. James Andrews is scheduled to perform an ulnar collateral reconstruction on Smyly's left elbow on July 6 in Birmingham, Alabama. Because the typical recovery time from a UCL reconstruction is 12-15 months, Smyly is likely to miss most or all of the 2018 season as well.
Smyly, 27, is 31-27 with a 3.74 ERA over parts of five seasons with the Detroit Tigers and Tampa Bay Rays. Seattle acquired him from Tampa Bay in January in a trade for shortstop Carlos Vargas, pitcher Ryan Yarbrough and outfielder Mallex Smith.
Smyly made three Cactus League appearances with the Mariners and pitched once for Team USA in the World Baseball Classic before going on the disabled list March 30 with a left arm flexor strain. The Mariners transferred him to the 60-day DL on April 4.