It would be another huge blow to a team that has already lost pitcher Chris Carpenter and shortstop Rafael Furcal for the season. The Cardinals pretty much stood pat after losing to the San Francisco Giants in the NL championship series last fall.
Motte, who had a career-high 42 saves last season, has been shut down since late March because of a strained right elbow. He wasn't cleared to throw after a second MRI exam Tuesday didn't show sufficient improvement and revealed a tear.
A first MRI exam was inconclusive because of inflammation, and Motte said range of motion and other indicators had improved somewhat.
"I'm still optimistic," Motte said after the Cardinals beat the Reds 5-1 Tuesday. "I'm not doing anything more to hurt it, so it's kind of out of my hands, honestly.
"We're doing everything we can to get it better."
General manager John Mozeliak said the team should have a good idea by early May whether the 30-year-old right-hander will be able to pitch this season.
"Surgery is definitely on the table if he's not throwing by then," Mozeliak said. "Rather than drag this thing out all summer, we put a soft deadline on it to find out."
The news comes a day after stand-in closer Mitchell Boggs was charged with six earned runs in one-third of an inning during Cincinnati's nine-run ninth. Other options include Fernando Salas, who led the team with 24 saves in 2011, and rookie setup man Trevor Rosenthal.
Motte signed a $12 million, two-year contract in January that avoided arbitration. He said Dr. George Paletta, the team physician, told him it's far from certain that he'll need surgery.
"We're going to keep doing the rehab stuff," Motte said. "Hopefully it helps me get better."
Before the team learned the news about Motte, manager Mike Matheny said it was too early to make any changes. Boggs was hurt by four walks - two intentional - in what he called "the worst outing of my career," but remained confident after Monday's 13-4 loss that he is the man for the job while Motte is out.
"Whenever you lose a guy like that it's tough on everybody, but at the same time we're professionals and we have a job to do," Boggs said. "I can't speak for anybody else, but speaking for me I've got to execute better. I didn't make enough good pitches, and there's nothing other to say than that."
It's no surprise to Matheny that players consistently deny feeling extra pressure when thrust into a new role.
"That's what they've been trained to say and what they're trained to do," Matheny said. "But the ninth inning is different, and a lot of guys who have been successful at it have also had struggles."
When staff ace Adam Wainwright was a rookie, he filled in as closer for the 2006 World Series championship team after Jason Isringhausen was sidelined with a hip injury. Wainwright earned the save in the Series clincher, and then joined the rotation the next year.
"So, it might not necessarily mean how you start but how you finish," Mozeliak said. "We may need more time and clarity on who that will be."
Mozeliak said he didn't anticipate Motte seeking a second opinion.
"A player has that right, but I think he feels pretty confident with what he's hearing," Mozeliak said.