With the exception of a short trip to San Diego, he hasn't left Arizona since, as he's been working to rehabilitate an elbow strain that sidelined him in April.
Kelly, 22, appears to have turned a corner in his rehabilitation. After a setback early on, he took three weeks off from throwing and took antibiotics that have helped. He's been pain-free ever since and on Saturday threw his first simulated game at the team's Spring Training facility in Peoria.
"The last two months have been good," Kelly said. "The recovery has been better. It's been really tough just because before that. It was a day-to-day thing to see how it felt.
"I think that I'm headed in the right direction."
Kelly, who began the season at Triple-A Tucson and made two starts before being sidelined, has thrown three bullpen sessions. After Saturday's simulated game, he'll likely throw another next week. If that goes well, he could pitch for the Padres' Arizona League team in the near future.
"You want to get back out there and start playing again," Kelly said. "But at the same time, there's no point if you're hurt. The elbow, the first couple of months, didn't feel right."
Kelly made two starts with Tucson in April and had a 2.25 ERA with 14 strikeouts in 12 innings with no walks. It was at that point where his elbow first began to bother him. He flew to San Diego for an MRI that revealed no structural damage. Then it was off to Arizona for rehabilitation.
"This thing has been so crazy," Kelly said. "It's really been up and down ... one day my elbow felt good, the next day it felt bad. It took a toll on me mentally. But I've had a lot of support from the trainers and my family and friends. It could have been worse. I could have ended up having surgery."
Now, Kelly has his eye on making up for lost time.
"I'm a competitor," he said. "It's hard to sit here and watching my teammates play online. I want to get out there and play. For me, innings-wise in my development, I need to pitch as many innings as possible."