"There's damage to the ulnar collateral ligament, the MRIs revealed, and he's to see Dr. [Lewis] Yocum [on Tuesday in Los Angeles] for a second opinion," Moore said.
If Soria undergoes the reconstructive surgery on his right elbow, it would knock him out for the 2012 season because the current recovery time is nine to 12 months.
Asked if that was a possibility, Moore said: "It could be, yeah, but we'll get another opinion from Yocum."
Soria was taken out of Sunday's game against the Indians because of elbow discomfort and underwent an MRI. He's had a tough time pitching throughout Spring Training.
He underwent Tommy John surgery early in his career when he was in the Dodgers' organization and missed the entire 2003 season.
"It's unfortunate, because Joakim is such a professional person and he's obviously hurting right now, but we'll just hope for the best, and if he does need reconstruction, which would be his second, let's hope for a good outcome," Moore said.
Manager Ned Yost said the Royals have two pitchers, former Dodgers closer Jonathan Broxton, and last year's setup standout, Greg Holland, who could replace Soria as the Royals' closer.
This is the second severe injury blow to a front-line player for the Royals this month. Catcher Salvador Perez underwent left knee surgery and might be out until the All-Star break.
Moore and Yost got the news on the Royals' off-day while they stood in the back fields of the complex. They had come to watch left-handers Jonathan Sanchez and Everett Teaford pitch and third baseman Mike Moustakas hit in Minor League games.
But Moore's cell phone buzzed on a brisk, breezy afternoon and brought the daunting results of Soria's MRI.
"That wasn't the news I wanted to hear," Yost said. "You knew that there was something in there that wasn't right. We'll see what Dr. Yocum says tomorrow, but it doesn't look very good.
"The one thing that we have to our advantage is that most clubs have one closer. We've got three possible closers. We'll just see how it plays out, but it's definitely a blow. He was the patriarch of our pitching staff, of our bullpen for sure."
Soria never got into a groove in camp and was even knocked around in an intrasquad game and a "B" game. In three Cactus League games, he had an 18.90 ERA and opponents hit .556 against him. In 3 1/3 innings, he gave up seven runs on 10 hits and one walk. He struck out three.
"When guys start to have problems, the first thing that goes is their command a lot of times, and Jack was throwing the ball with good velocity, but he just wasn't the Jack that we've known -- where he's been able to get out and extend on his pitches," Yost said.
"It was puzzling why that was the case. This [injury] is probably a big reason why. He'll tell you he wasn't in any pain, he wasn't in any discomfort until yesterday. But a lot of times, it's like a volcano. You feel the seismic rumblings and then all of a sudden, it blows. And the ability to not command the ball like we know that he can is seismic rumblings."
Soria, 27, is a two-time All-Star who has 160 saves in his five seasons with the Royals, reaching highs of 43 in 2010 and 42 in '08. He was picked up by the Royals from the Padres in the '06 Rule 5 Draft and became a full-time closer at midseason of his rookie year in '07.
Early last season Soria had problems and, after blowing four of five saves in late May, removed himself from the closer's role for a few games while he worked on his mechanics. Resuming the role on June 9, he was 21-for-23 in save chances after that and finished with 27 saves. But he had his poorest season in terms of blown saves (7), losses (5), ERA (4.03) and home runs allowed (7).
Even so, Soria was the leader of a rookie-dominated bullpen during the 2011 season.
"Just his presence down there in the 'pen with these guys was so valuable," Yost said. "But, you know what, he's taught them well, and it's not like he won't be with us. So we'll just work through it and see what we've got and go from there."
What he's got is Broxton, himself a two-time All-Star with the Dodgers, and Holland, who became the Royals' top reliever down the stretch last year. Both are right-handers.
"It's a big blow to our staff but, thankfully, Dayton has done a good job of getting us depth and putting us in a situation where this doesn't kill us," Yost said.
"They both can handle it, and we'll think through it. It wasn't a scenario that I could foresee coming, so it's going to take some thinking through it to see which way it sets up best. We may use them both in that spot, I don't know."
Holland last season had a 1.80 ERA and led the Majors by permitting just two of 33 inherited runners to score (6.1 percent). He finished with a 5-1 record, four saves and held opponents to a .175 average.
Broxton missed most of last season with bone spurs in his right elbow and had them removed in September. When the Royals signed him as a free agent, they got a pitcher with a history of 84 saves and 503 strikeouts in 392 innings.
"They've both looked great this spring," Yost said. "We'll give it time to play out. We could very well use both of them in that situation. I've got the confidence to use both of them -- I think they both can handle it."
Holland, in five Cactus games, has a 1.69 ERA and two saves with one run given up on three hits in 5 1/3 innings. He's struck out seven, walked none and held opponents to a .158 average.
Broxton, brought in slowly because of his September surgery, has pitched in two games. In two innings, he hasn't given up a run or a hit with one walk and three strikeouts.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.