That injury initially was diagnosed as a strain of the latissimus dorsi muscle, running from the posterior to the arm. But knowing himself as an athlete and a competitor, Peavy understood this problem was more than a strain.
"I knew something was wrong when I walked off the field," said Peavy, speaking to a mass of media in front of his locker prior to Wednesday night's game. "I told you guys from the get-go, if you see me not being composed, starting to walk off the field, like I did last night, you know obviously it's not good news."
Suffering a detached latissimus dorsi muscle, as an MRI revealed on Wednesday, certainly would fall under the bad-news header. It's a potentially season-ending injury, with surgery a definite possibility, according to Peavy.
Peavy already had planned to go home to Alabama over the All-Star break. That trip now will include a visit with renowned surgeon Dr. James Andrews, and Dr. Lewis Yocum also will be consulted, according to Peavy, due to the somewhat unknown nature of this injury.
"Our doctor, simply because of the nature of the injury, wants to have input from other doctors," Peavy said. "I think with it being completely off the bone and retracted ...
"It's just one of those things. I asked the doctor, 'Is there anything I could have done to have prevented this?' He said, 'You could have done all the shoulder exercises you could do.' I've been doing the shoulder program, it's just something that it's a rarity. That's one of the tougher things.
"If you tear your labrum or your rotator cuff or have Tommy John, that's clear-cut. It's very common, you know what surgery it is, you know the time table," Peavy said. "I think all the uncertainty around this is what is bothersome to me. But at the same time, obviously we've been fighting this thing for quite a while and thought we can maintain it. I was preaching that."
This injury might be rare, but it's not the first physical issue Peavy has fought through this season. About one month ago, the right-hander dealt with a dead-arm period.
When the team was in Pittsburgh, Peavy was bothered by soreness in his shoulder and had an MRI done on June 15. The MRI revealed fluid build-up, and his start was moved back two days from Pittsburgh to Washington.
Manager Ozzie Guillen wanted Peavy on the disabled list at that point, even though the veteran bounced back and threw a shutout in a 1-0 victory over the Nationals. But even factoring in Tuesday's rough result, Guillen doesn't feel bad about not pushing harder to make Peavy inactive.
"No, no. I argued my point for two hours," Guillen said. "Our general manager and our pitching coach were on top of that. We addressed the problem. If this problem was in Washington, then I would say, 'Wow, what did we do?'
"He was throwing the ball very well. It just happened. But no, we talked about it and we discussed it. I gave them my ideas, [GM] Kenny [Williams] gave me his ideas. Our pitching coach has a Plan C. That means we don't feel guilty about it.
"One thing happened and we have to continue without him. Nobody should feel guilty or responsible for what happened to him. We talk a lot about that and I had a lot of experience with it. That's why we spent a lot of time to convince him."
Guillen's sentiment was echoed by Peavy.
"Hindsight is 20/20. We certainly would have shut it down even before Pittsburgh," Peavy said. "Like I said, it was moving it around, this was almost in an area different than the other ones. So I don't think anybody made any bad choices here. We did all we thought we could do.
"Sometimes stuff happens and when you pitch and play as long as I have, I was fortunate not to have an injury like this sooner. But it's happened and we've got to make the best of it now. We're obviously going to weigh our options the next few days and make an educated decision on what's best. But I don't think anyone is at fault here -- myself for wanting to be out there or the team for letting me be out there."
During Peavy's last start prior to Tuesday, in Kansas City on June 30, Peavy felt something grab in the area of Tuesday's injury. There was also some bruising in that region.
Treatment was given to Peavy for the problem, and he felt ready to go. Pain replaced that thought when Peavy threw a 2-2 pitch to Mike Napoli with one out in the second Tuesday, reaching at the area of the injury and walking off the field before Guillen and head athletic trainer Herm Schneider could reach him.
Now, the White Sox most likely will have to fight toward the postseason without their projected ace, who posted a 3-2 record and 1.67 ERA over his last six starts. Daniel Hudson figures to be his replacement from Triple-A Charlotte, unless Williams puts a veteran pitcher on his trade radar.
Whatever the call, the White Sox believe they will survive, while Peavy is looking for more information before making a call on 2010.
"You don't want to lose one of your main guys," White Sox pitching coach Don Cooper said. "Jake was a great part of what we are doing and what we want to accomplish. But the bottom line is he's gone, and my sights are no longer on him.
"Don't get me wrong: I feel terrible for him, and I know he wants to compete. But he's in a situation where we are going to have to find out more about it and take care of him. That's the long and short of it."
Scott Merkin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.