A year removed from a 2017 campaign defined by blister issues and struggles on the mound, Johnny Cueto's season has once again ended on a sour note.

The San Francisco Giants right-hander underwent Tommy John surgery to repair the torn ulnar collateral ligament in his elbow and is expected to miss all of 2019.

It was originally believed Cueto was dealing with a sprained elbow before it was discovered he had been pitching with the UCL completely torn. Somehow, his fastball still approached 90 mph in his final start, with one pitch even hitting that plateau.

That feat left Dr. Neal ElAttrache amazed and confused.

"I don't know how you were doing it," Dr. ElAttrache told him. "Other than the fact that you're you."

After initially trying to pitch through the pain, it became too much, according to The Athletic's Andrew Baggarly.

"I feel really bad. I surely want to try to help the team," Cueto said through Spanish interpreter Erwin Higueros. "I want to go out there like a warrior and give my best. But I keep telling you guys and keep telling myself that I'm fine and in reality I'm not. And I just feel sad that I can't help. It's very difficult every time I go out there."

If Cueto is indeed unable to return until 2020, he will be entering his age-34 season having pitched just 200 1/3 major-league innings in the previous three campaigns. The veteran right-hander remains under contract with the Giants through 2021 plus an additional $22-million team option for 2022 with a $5-million buyout.