"It creeped up on me a little after that game," Irwin said of the fingers numbness and elbow pain following that April 14 start in PNC Park. "Then it increased over the next few days."
The right-hander returned to Indianapolis, but he couldn't make his next start. He tried a couple weeks later, but couldn't get past the fourth inning.
Soon, Irwin underwent ulnar nerve transplant surgery.
"That's about a half of the Tommy John," Irwin, smiling, said of the better-known procedure involving the ulnar ligament transplant.
Irwin should know: He had the Tommy John job in 2005, when he was still in Christian Brothers High School in Memphis, Tenn. Irwin came back from that -- he went 13-4 with a solid 3.14 ERA in 24 Minor League starts in 2011, two years after the Bucs selected him in the First-Year Player Draft -- so is confident of being on the way to another full recovery.
"Everything feels good now. All the numbness is gone, there's no pain. Now it's just a matter of trying to work out some mechanical issues," Irwin said after going 2 1/3 innings in his fourth Arizona Fall League start. "This is almost like my Spring Training, just trying to figure out some things and making sure there are no setbacks with the elbow. Just get in some innings, get ready for the real Spring Training."
That April 14 spot start came in place of Wandy Rodriguez, who had to skip a turn with a minor hamstring strain. Irwin could be a candidate as a more permanent replacement for Rodriguez if the lefty hits more roadblocks in his comeback attempt from forearm arthritis -- or for A.J. Burnett, whose 2014 plans are in limbo.
Irwin follows those offseason developments with understandable interest, but also with restraint.
"Whether those guys are there or not, I still have to go out and compete and pitch my way onto the team," he said. "They're not just going to hand me the spot if they're not there. And even if they aren't, I know they'll probably go out and get somebody else. [Manager Clint Hurdle] likes veteran guys, and that's a big reason we had the year we had."
Irwin appeared on the way to his own good year before, as he put it, he had to "hit the reset button." An impressive Spring Training put him in position to be the first callup from Triple-A when help was needed.
"I was groovin', feeling really good," Irwin said, "and had everything working for me. So the setback was tough to deal with but, since I already had the TJ, at least I was familiar with surgery and what you have to do to get back.
"There's a lot of rehab, and then you have to get out there and convince yourself that you're healthy. First time out, you're pretty timid, not sure how it's going to go. And you usually develop some bad habits from trying to protect your arm. That's why, early in coming back from TJ, so many guys start out with shoulder problems -- that's from trying to protect the elbow. You just got to keep going out there and work things out."
Hoping that things will still work out for him, Irwin has made his final appearance in the AFL, which wraps up its short season this weekend. In four starts, he has stretched out as long as four innings, and has totaled 11 strikeouts in 11 2/3 innings. He joined Scottsdale as a replacement for Jameson Taillon after the Pirates' No. 1 prospect tweaked his groin in his first start.
That might have been the first good break Irwin had gotten in a while.
"I would think they would've wanted me to pitch somewhere competitively," he said of giving the Pirates staff a better idea of what to expect going into Spring Training.