Spencer Kieboom (Courtesy of Matt Stahley of Sportstar Designs via Hagerstown Suns) Spencer Kieboom (Courtesy of Matt Stahley of Sportstar Designs via Hagerstown Suns)

Several of the non-roster players invited to big league spring training have interesting back-stories. Most are veterans hoping to jump-start their careers. Some are players hoping to nab one of the last available spots on the team and some are minor leaguers that could benefit from the big league camp experience and coaching. This year, the Nationals’ non-roster invitees list includes few prospects — only two — and that’s because some of the organization’s best are already on the 40-man roster.

One of those prospects, Spencer Kieboom, a 23-year-old catcher drafted out of Clemson in the fifth round of the 2012 draft, may be among the most intriguing players in camp simply because of his experience and his bat. He and infield prospect Wilmer Difo, who is on the 40-man roster, both finished last season at Class A Hagerstown but now find themselves in big league camp. Now he’ll be one of seven catchers in spring training, including top defensive catching prospect Pedro Severino.

Kieboom’s best trait is his bat. Offensive catchers are hard to find and Kieboom had a fine all-around season in 2014, his first back from Tommy John surgery. Kieboom hit .309/.352/.500 with nine home runs and 61 RBI in 87 games last season. His .852 OPS was best on Hagerstown, which reached the South Atlantic League finals. Missing nearly all of 2013 with the surgery sparked Kieboom’s offensive improvement.

“It was a blessing in disguise,” Kieboom said in November during the Arizona Fall League, where he played on the Mesa Solar Sox along with other Nationals prospects and minor leaguers. “It gave me the opportunity to really focus on my hitting and really focus on my swing and what works for me. It’s just been one of those things it turned out the way it did in the sense of I was disappointed. That’s an understatement of how I felt in 2013. I don’t think I could have come back and had a better year. I couldn’t have written any better myself. It’s nice to swing the bat.”

The original problem arose when Kieboom was long-tossing in his native Marietta, Ga., before the 2013 season. He felt something weird in his throwing arm. “Didn’t think twice about it because there was no tingling or signs or symptoms,” he said.

But two weeks later, Kieboom’s arm felt weird. He couldn’t throw. The ulnar collateral ligament ripped completely off the bone. He became one of the few position players to need Tommy John surgery. Doctors took a ligament from his wrist to repair his elbow. During rehab, Kieboom followed the same plan as the pitchers who had the surgery, such as his close friend and Hagerstown roommate Lucas Giolito.

The mental part of the rehab challenged Kieboom the most. But his physical limitations during rehab helped him become a better hitter, he said. He swung the bat one-handed. He found a more comfortable set-up in the batter’s box. He got tips from vice president of player personnel Bob Boone and minor league hitting coordinator Troy Gingrich but something that Class AA Harrisburg hitting coach Mark Harris said stuck with him.

“Instead of trying to stop what’s wrong, it’s about figuring out what’s causing it,” Kieboom said. “Instead of saying, don’t bail out or step out, maybe I’ll shift weight forward. If I know what the problem is, don’t say ‘don’t do that’ but diagnose what’s causing it and that’ll help fix it.”

The sharpened self-awareness and adjustments helped. Only in his third professional season, Kieboom had his best season yet. He is a solid defender, too, with a good arm. Sure, he may be 23 and only now finishing his first full season at low-Class A, but Kieboom doesn’t worry about how his development was stunted a year by the surgery. Now, he gets to come to his first big league camp to get a taste of the coaching, pitching and games.

“The only thing I can control is on the field,” he said. “The rest is out of my hands. Of course, I want to move fast and do certain things. I’m not going to play upset and with a chip on my shoulder. I just go out and play. It is what it is. All I can do is play and prepare every single day.”