Threets left Friday's 9-4 victory over the Yankees after throwing a pitch in the ninth inning, departing with an injury not specifically showing up on X-rays. An MRI Saturday revealed Threets suffered a torn ulnar collateral ligament in his left elbow, and he was placed on the 15-day disabled list.
Although the problem wasn't specifically diagnosed on Friday, White Sox manager Ozzie Guillen knew it was nothing good.
"When that happened, I got the feeling he knew because when I went out there, he didn't know what to say," Guillen said. "I got the bad feeling that, 'Wow, I think this kid knows what he got.'
"In the meanwhile, it's a shame, because he has a good arm. He was helping us, and he had a great opportunity with us. Very, very sad moment."
The injury produced the third trip to the disabled list since Wednesday for a White Sox reliever. With all due respect to the 28-year-old Threets, the first two setbacks -- to J.J. Putz and Matt Thornton -- served as a bigger potential hits to the White Sox playoff chances.
Putz was beset by right knee patella tendinitis, while Thornton was diagnosed with left elbow inflammation. Despite Putz leaving the game after three pitches on Tuesday and Thornton not pitching since giving up a walk-off home run to Jim Thome on Aug. 17, pitching coach Don Cooper expects them back as soon as they are healthy.
"Once they get back, we are going to throw them right in more than likely," said Cooper of Putz and Thornton. "I don't believe you are going to see either one on a rehab assignment, that's my guess.
"I'm certainly not in charge of that one. Matt is feeling better, and will have a sideline soon. After a couple of those, we should be able to run him back out there. He's just going to be out there for an inning. It won't take really long once we get him feeling good."
Carlos Torres has been called up from Triple-A Charlotte to replace Threets. Torres lost a spot-start on Aug. 3 in Detroit, but some in the organization believe Torres is better suited as a setup man. Lucas Harrell has already been added from Charlotte, and rookie Chris Sale will be counted on to play more of a serious late-inning role.
Guillen isn't worried about Sale moving into such a crucial spot after pitching for Florida Gulf Coast University a little over two months ago.
"One thing this kid has shown in the big leagues is he's not afraid," said Guillen of Sale. "A lot of people talk about it, but when you have that kind of stuff, you shouldn't be afraid. He has a great chance to be a very good one."
As for Threets, he will see Dr. Lewis Yocum on Tuesday to decide the next course of action. Factoring in the Minor Leagues and a previous stint this season, Threets has made 11 trips to the disabled list.
The maladies have included everything from turf toe to a tear in his left shoulder. This particular injury seemed to hit Threets especially hard.
"I've been humbled so many times by this game that I was hoping to get some payback," said Threets, who admitted he has been a little bit tight all season and dates this injury back to a flexor tendon tear last year. "I've put up numbers and feel like I've finally got to the point where I can consistently get outs. I've got my mind there, it's just physically it hasn't cooperated quite yet. But when it does, I know that I'll be more than effective."
"He's got a long way [to go]," Guillen said. "After surgery, I hope he comes back better. A lot of people say after that surgery you come back better. We'll wait and see.
Scott Merkin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.