"Just unfortunate," manager Don Mattingly said before Tuesday night's game against the New York Mets.
Billingsley will have the elbow-ligament transplant operation Wednesday in Los Angeles. The team said it typically takes about 12 months to return to competition.
Billingsley was 1-0 with a 3.00 ERA in two starts this season. He was scheduled to start last Sunday in Baltimore, but instead was put on the 15-day disabled list because of elbow pain.
The 28-year-old Billingsley joined three other Dodgers starters already on the disabled list: Zack Greinke (left fractured clavicle), Chris Capuano (left calf strain) and Ted Lilly (left shoulder surgery).
Lilly is set to come off the DL and start Wednesday night in New York, a day after former NL Cy Young Award winner Clayton Kershaw pitched against the Mets.
"You're probably going to need eight-to-10 starters," Mattingly said. "You probably wouldn't think you'd need them in the first 20 days."
Billingsley hurt his elbow last August, didn't pitch after early September and decided to try rehabilitation and a platelet-rich plasma injection instead of major surgery. He had been fine until feeling pain last Friday in a bullpen session. An MRI showed the injury.
"I think he was pretty confident coming into the spring. He had a great winter and was able to throw," he said. "I think he was more confident than we were."
Mattingly said the Dodgers began to echo Billingsley's optimism in spring training. Billingsley bruised the index finger on his right hand during a bunting drill on March 15, slowing his return.
Billingsley is 81-61 with a 3.65 ERA in eight big league seasons, making him the longest-tenured Dodgers pitcher.
"I'm sure he's disappointed," Mattingly said.
Billingsley's jersey hung in his locker at Citi Field. The team said he wasn't at the ballpark.
Mattingly declined to say whether Dodgers management regretted not pushing Billingsley to have surgery last year.
"I can't really speak for the medical department," he said. "You can't make a guy do anything. The fact that it was working was encouraging to him."
The Dodgers began the day at 8-10, not quite what they expected after a major, high-priced overhaul that started late last season.
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