ARLINGTON -- The Angels' worst fears about JC Ramirez were confirmed on Monday, as the 29-year-old right-hander was diagnosed with a torn ulnar collateral ligament in his throwing elbow and has been advised to undergo Tommy John surgery.The standard timetable for ligament-reconstruction surgery is 12 to 16 months, meaning Ramirez

ARLINGTON -- The Angels' worst fears about JC Ramirez were confirmed on Monday, as the 29-year-old right-hander was diagnosed with a torn ulnar collateral ligament in his throwing elbow and has been advised to undergo Tommy John surgery.

The standard timetable for ligament-reconstruction surgery is 12 to 16 months, meaning Ramirez would miss the rest of the 2018 season should he opt for the procedure.

Ramirez missed the final six weeks of last season with a partially torn UCL and underwent stem-cell therapy in an attempt to heal his damaged elbow. At the time, Ramirez's tear was not severe enough for a recommendation of Tommy John surgery.

The stem-cell treatment initially seemed to take, as Ramirez got through Spring Training without incident and secured a spot in the Angels' Opening Day rotation. But he was forced to exit his second start of the season on Saturday after two innings with forearm tightness. Ramirez, whose fastball averaged 95.9 mph in 2017, maxed out at 92.5 mph during the shaky outing.

Medical update on RHP JC Ramirez:



“After clinical examination and imaging, JC Ramirez has been diagnosed with a torn ulnar collateral ligament. Based on these findings, UCL reconstruction is the recommended plan of care.” — Angels (@Angels) April 9, 2018

Ramirez emerged as one of the most pleasant surprises of the Angels' 2017 campaign by logging a 4.15 ERA over a career-high 147 1/3 innings in his first Major League season as a starter. He finished with nearly twice the amount of innings he had thrown in '16 after making the successful transition from the bullpen to the rotation.

"It's tough," Angels manager Mike Scioscia said on Monday. "It's a shame. This guy worked very, very hard. It definitely knocks the wind out of you when you see a guy who worked as hard as he has and has to miss a whole year. In the big picture, he's learned so much about himself and about pitching in the last season that hopefully he'll pick it right up next year this time and be better for it."

The news on Ramirez continues a troubling trend of rotation injuries for the Angels, who already have Matthew Shoemaker (right forearm strain) and Andrew Heaney (left elbow inflammation) on the disabled list.

Shoemaker was scheduled to undergo more tests on Monday in Los Angeles to determine the source of his forearm discomfort, while Heaney threw a bullpen session at Globe Life Park on Monday and said afterward that he feels he's ready to go. Heaney will likely rejoin the rotation during the Angels' upcoming series in Kansas City, though the club has not yet made an official announcement.

The Angels are also hoping to receive a boost from pitching prospect Jaime Barria , who will be called up on Wednesday to make his Major League debut against the Rangers. Ranked the Angels' No. 7 prospect by MLB Pipeline, the 21-year-old right-hander compiled a 2.80 ERA over 141 2/3 innings while ascending from Class A Advanced Inland Empire to Triple-A Salt Lake in 2017.

"As Jaime's spring went on, you saw the talent," Scioscia said. "He's got terrific in-zone command of the baseball. He's able to move the ball around and changes speeds very well. He's really sneaky with his fastball."

The Ohtani brief

Two-way phenom Shohei Ohtani , who was named the American League Player of the Week following his 12-strikeout gem against the A's on Sunday, will be available to hit on Tuesday, but Scioscia said the Angels still have not decided whether he'll be in the starting lineup against Rangers left-hander Martin Perez . Ohtani has homered in three straight games as the Angels' designated hitter, though he has not batted since Friday.

Kinsler close

Second baseman Ian Kinsler (left adductor strain) ran the bases and took ground balls during a workout at Globe Life Park on Monday. Kinsler is eligible to come off the DL on Tuesday, but he said the Angels still haven't decided when he'll be activated.

"It's responding completely up to this point," Kinsler said. "Now it's just trying to make the best decision possible."