"He couldn't get loose," manager John Gibbons said Friday. "The arm was dead and something wasn't right."
The Venezuelan native was an important part of the Royals' bullpen last season, going 4-2 with a 3.18 ERA in 67 appearances while holding left-handed hitters to just a .192 average. With Aaron Loup starting the season on the 15-day DL with a strained left flexor tendon, the injury to Morales leaves Brett Cecil as Gibbons' lone left-handed option in the bullpen.
Estrada, who signed a two-year, $26 million dollar deal this past offseason to remain in Toronto, missed the majority of Spring Training after injuring his back early in camp and started the season on the DL. The 32-year-old made 34 appearances -- including 28 starts -- for the Blue Jays in 2015, compiling a 13-8 record with a 3.13 ERA.
Alykhan Ravjiani is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.