The 21-year-old Kelly has essentially been in listen-and-learn mode so far, attempting to soak in as much information as he can from coaches and players.
Only pitchers Matt Lollis and Juan Oramas, both 20, are younger than Kelly.
So far, Kelly said, so good.
"It's been a great experience so far ... being out here and being around the guys. You're trying to learn as much as possible and soak in as much as you can," Kelly said. "You're trying to pick up as many things as you can for the season."
To date, Kelly has thrown three bullpen sessions, like the other pitchers here in camp. He has impressed the staff with how he's handled himself in his first Major League camp -- and he's impressed them with his athletic ability and pitching prowess.
"The thing that is so exciting for me is that he's athletic," Padres pitching coach Darren Balsley said. "That will allow him to repeat his delivery and make adjustments on the mound. He moves really well and has good body control.
"He's got a very smooth delivery. It looks like he throws harder than he does. He's got good arm speed with a little late life."
Aside from working with Balsley and manager Bud Black, who, of course, is a former Major League pitcher, Kelly has drawn from the wisdom of three former players who are now working in the Padres' baseball operations department.
"Just being around Trevor Hoffman, Brad Ausmus and Mark Loretta, you listen to them talk and ask them questions whenever you have them because they are the best guys to ask," Kelly said.
"And just being around the other guys, it's a great to be around them and pick up a few things for the season."
Kelly, who has thrown 190 innings over the last two seasons, is likely headed to Double-A San Antonio to start the season. But the Padres say Kelly, because of his ability and aptitude, could move fast.
Because he threw 95 innings last season in his first full season as a pitcher -- Kelly was drafted as a shortstop -- the Padres won't likely let him go past the 150-inning mark this season.
At some point next month, Kelly will be moved over to the Minor League side, probably after pitchers and catchers report on March 4. He won't soon forget his time in the big league clubhouse, even if it's here in Peoria and not San Diego.
"It's been good and we'll hopefully keep it going in the next few weeks," Kelly said. "I think everyone in that clubhouse has been through everything, going through the Minor Leagues, going through ups and downs.
"For me ... it's how you deal with it, how you learn from it and how you make yourself better."