"Everyone wants to be successful. Everyone wants to be good. But there are times where baseball puts you on your butt and you have to get up and go try again," Kelly said. "Even last year, there were a few times where I'm like, 'What's going on?'
"But later in the season, and in a similar situation, I learned how to get out of it. I think you go through some tough times, but in the end, it makes you better."
This is the hope held by the Padres, who are looking for big things from the 22-year-old right-hander as he heads into his third full professional season of pitching after making the conversion from shortstop following the 2009 season while in the Red Sox system.
There's no denying Kelly's stuff: fastball, curveball and changeup -- pitches that on occasion can rate as electric. There's also no denying Kelly's advanced makeup, his smarts as well as his athleticism -- he was a highly touted quarterback in high school who bypassed a chance to play in college to sign with Boston.
The Padres thought highly enough of Kelly to insist that any prospective deal with the Red Sox begin and end with Kelly's inclusion.
But now, after two full seasons of pitching professionally, the Padres would like nothing more than to see Kelly put all the pieces together. The organization would like to see him improve his hits per nine innings (career 9.1, 9.7 in 2011) and show more consistency moving forward.
"His challenge is to command that movement of his fastball and locate it at a little higher rate than he's done early in his career," Padres manager Bud Black said. "For Casey, the ball moves. But it's the ability to have the feel and command of the ball. It comes down to consistency.
"The competitiveness is there. The athleticism, the heart is there. He's just got to make better pitches."
To that end, the Padres have moved him to the left side of the pitching rubber this spring with the hope of creating more deception in his delivery. They have asked him to speed up his tempo as well and use his legs more. These are subtle changes that the organization hopes can lead him to a big 2012 season.
Kelly, who even as he enters his third season as a pitcher, still feels like a sponge as he works through camp. He's soaking in all of the information that he can from Black and pitching coach Darren Balsley, among others, and realizes he's nowhere close to being a finished product.
It's almost enough to make him wistful for shortstop again -- almost.
"There were times last year when I was really frustrated and wanted to be better, have better numbers," Kelly said. "But at the same time, you step back and look at the big picture and know that while I might not get it or understand it, that later on down the road it's going to help."
Kelly was much better last year than he was his first full season as a pitcher in 2010. He was 11-6 with a 3.98 ERA in 27 starts. His innings increased from 95 in 2010 to 142 1/3. Kelly allowed 153 hits over that same stretch with 105 strikeouts and 46 walks for a Double-A San Antonio team that won 100 games on its way to winning the Texas League championship.
"I think last year was a big step in building on what I did the previous year," Kelly said. "Those numbers were better than they were the year before. Mentally, it was learning how to pitch ... going out there every fifth day, trying to be as consistent as possible. Those things came into play in 2011. I'm excited that 2012 is going to be even better."
Not all of the adjustments Kelly has made or is making are mechanical, though. Some of the best adjustments, and the most important ones, occur between the ears, as Kelly has found himself in foreign situations, ones that won't be so unfamiliar once he goes through them more. It's that whole no-substitute-for-experience thing.
"You get in some tough situations where you give up a leadoff double or have guys at first and second with one out," Kelly said. "It just taking a deep breath and not let the game speed up on you, taking it one hitter at a time instead of worrying about how to get two outs or how am I going to get out of this? Sometimes, you sacrifice one run instead of four."
It's a lot to think about and an awful lot to work on, though there have been signs that Kelly is getting there. Maybe not as quickly as he would like, but he's getting there.
"For the most part, he's at his best when he's able to locate his fastball," said Jason Hagerty, who caught Kelly in the second half last season. "Once he located his fastball, he did fine. He made adjustment from start to start. You can tell he's got a lot of confidence.
"The fact you could see him make adjustments is really good. I think that he's on the right track."