The Rays transferred Smyly to the 60-day disabled list Wednesday, and said Dr. Keith Meister will examine his torn labrum in Texas on Thursday.
"It's frustrating. I guess we've been prepped pretty good on how to handle it," manager Kevin Cash said about a week after the Rays learned Alex Cobb will have Tommy John surgery. "Obviously, it's a devastating blow. We don't know much more beyond that, but we knew it was going to take some time for (Smyly) to get where he needs to be to help us."
The 25-year-old Smyly came back from a spring bout of tendinitis to make three starts, but he began complaining of tightness in his arm during a start at Boston on May 5. He is 0-1 with a 2.70 ERA.
The Rays began the season without starting pitchers Smyly, Cobb and Matt Moore, who had Tommy John surgery on April 22, 2014.
Moore, who won 17 games in 2013, took another step toward his targeted June return Wednesday, throwing 16 pitches to hitters and then 18 more with a five-minute break in between. He will do that again in five days, after which the Rays will decide whether to put him on a rehab assignment.
The Rays plan to activate closer Jake McGee this coming weekend. He had elbow surgery in December.