Escobar and the Angels made the decision to have surgery on Friday after consulting with team physician Dr. Lewis Yokum and a shoulder specialist in New York.
"As this week went on, we all felt that it was moving in that direction, to have surgery," manager Mike Scioscia said before the Angels played Oakland. "We all saw how hard Kelvim worked through spring. He was smiling when he came back to us and was in rehab starts. We all felt there was no question he was going to pitch for us in some capacity this year."
Escobar instead will have surgery sometime before the end of July to correct the pain in his right shoulder. The 32-year-old, who won 18 games last season, was first diagnosed with the injury in March but held off on surgery in hopes that the problem would go away with rest and rehab.
It seemed to be working. All indications were that Escobar was making progress and had recently begun a rehab assignment for Class-A Rancho Cucamonga. In his only appearance for the team on June 30, Escobar gave up one hit and struck out four over three shutout innings.
Though no official date has been set for Escobar's surgery, an Angels spokesman said the typical timetable for recovery is nine to 12 months.
"If anyone's going to come back from this, it'll be Kelvim," Scioscia said. "This guy's an incredibly hard worker and he wants it."