Lefty Steven Rodriguez, who was drafted this year in the second round out of the University of Florida, had his contract selected by the team from Double-A Chattanooga in a corresponding move.
Billingsley, who was originally placed on the 15-day DL on Aug. 25, had a second platelet-rich plasma injection Wednesday and the right-hander will begin a throwing program in two weeks.
If the injection doesn't heal the "slight tearing," then there is a chance he would need offseason surgery, likely Tommy John, which would keep him out for 2013. Having not picked up a baseball in two weeks, Billingsley had no idea what percent of a chance there is for surgery and he didn't want to speculate.
"He's in the partially torn category, so we have time to do these therapies," head trainer Sue Falsone said. "He's definitely making progress. There is less pain and it's less sharp."
With the UCL taking four to five weeks to heal and Billingsley about two weeks removed from the injury, he expects to find out once he starts trying to throw if surgery will be needed.
"There was an outside chance I may be able to get back," said Billingsley, who found out he would be shut down Monday night. "It wasn't very good, but I was able to hold onto that."
He agreed to a three-year, $35 million extension last year that keeps him signed through 2014, with a $14 million club option for 2015.
The news, which would be disappointing for any pitcher, is especially tough for Billingsley. Not only are the Dodgers in the thick of the division and Wild Card races, but he was pitching as well as he ever has in his seven-year career when he went down.
The righty had gone 6-0 while giving up just six runs in six starts after missing his first post-All-Star break start with a quick DL trip for an unrelated elbow injury to his flexor muscle. In the fourth inning against the Marlins on Aug. 24 after giving up three runs, Billingsley felt something wrong in his elbow and he hasn't pitched since.
Billingsley was wildly inconsistent through the first half of the season, but he turned things around and gave the Dodgers a reliable No. 2 pitcher behind Clayton Kershaw.
He finished the season 10-9 with a 3.55 ERA in 25 starts.
"Once he came back, the biggest difference was walks," manager Don Mattingly said. "He hardly walked anybody. He threw strikes with his fastball, got ahead in the count. He didn't get himself in a bunch of bad situations."
Now with Billingsley done for the season, Josh Beckett moves into that No. 2 role with his big-game experience and past track record.
The newly acquired righty struck out nine in 6 2/3 innings of one-run ball in his last start, and he gets the ball Friday in the series opener against the first-place Giants in San Francisco.
In the meantime, Billingsley said he will be traveling with the team every step of the way as the Dodgers make a push for the playoffs.
Frustrated he can't be on the field helping them, the veteran is ready to step into a cheerleader mode for his teammates.
"I can't be going too crazy with the high-fives," he said with a laugh trying to keep his spirits up.
In Billingsley's place comes Rodriguez, who is only three months removed from being drafted out of the University of Florida. He threw a bullpen session in front of coaches at Dodger Stadium on Wednesday afternoon and the roster move came not long after.
Batters hit only 7-for-47 (.149) off Rodriguez in Double-A in 13 2/3 innings. He posted a 2.19 ERA in 86 games with the University of Florida.
"As soon as he's ready and as soon as we need him, if we need him, I think he can be more than a left-on-left guy," said Logan White, the Dodgers' scouting director and assistant general manager. "I don't see why he doesn't have the stuff to pitch in any role you want out of the bullpen."
Alex Angert is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.