Lucas Giolito talks to the media during practice at the Nationals spring training camp on Tuesday. Giolito was taken 16th overall by Washington in the 2012 draft, three spots ahead of St. Louis right-hander Michael Wacha. (John McDonnell/The Washington Post)

Washington Nationals hitting coach Rick Schu likes to tell a story about 19-year-old right-handed fireballer Lucas Giolito. Early last July, before he was promoted to his current job, Schu was a roving hitting coordinator in the organization’s farm system. And one day, he was watching game video of the Nationals’ Gulf Coast League affiliate from July 3, which also happened to be Giolito’s first game back from Tommy John surgery only 11 months earlier.

Schu saw Giolito’s fastball — “electric,” he called it — behave almost like a sinker, dropping low in the strike zone, late and hard. In the pitch-tracking device, the pitch was labeled a four-seam fastball, normally a flatter pitch, but Schu was convinced it was a two-seam fastball. Schu even called coaches to double check. No, it was a four-seamer, he was told, and it actually moves that much. The Nationals’ top prospect, and among the top 100 in baseball according to most lists, was hitting the high 90s on the radar gun.

Seven months later, stronger and further removed from surgery, Giolito looks every bit the part of an elite pitching prospect, and prospect bible Baseball America tabbed him No. 21 overall . He looks like a small NBA power forward at 6 feet 6, 255 pounds, sports big hands that help him spin the baseball, is still maturing physically and touched 100 late in the season. The Southern California kid with Hollywood roots and a rocket arm is ready for his first full season in the minors.

“He is a can’t-miss,” Schu said. “Only come around once in a while.”

A year ago this time, Giolito was in the early stages of his throwing program after surgery. He picked up a baseball for the first time after the operation on Feb. 6. By mid-March, he was playing catch at 120 feet. He watched other minor leaguers play in intrasquad game and throw bullpen sessions. He yearned to be back on a mound. Now, he is back at the same minor league complex and going through the same throwing programs as every other minor league pitcher.

“It’s the best feeling in the world,” said Giolito, who added 10 to 15 pounds of muscle in the offseason. “I’m ready to go. I’m ready to get going. It’s just great that I was able to persevere through everything. I never had a setback. So it’s great.”

When the Nationals drafted Giolito out of Harvard-Westlake High with the 16th overall pick in the 2012 draft, the team knew he could go under the knife. Fifteen teams passed over him because of concerns over his elbow, but some believed he had the potential to be the top overall pick if he wasn’t hurt. The Nationals selected Giolito three picks before the St. Louis Cardinals took 2013 postseason star Michael Wacha, but they say they have no regrets.

“He’s got the tools, he’s got the ability but now it’s a matter of time and going through and sticking with the program and the ranks of the minor leagues,” Nationals farm director Mark Scialabba said. “But certainly very impressed with how he came into camp physically and he’s still maturing physically. Mentally, he’s very mature.”

Giolito passed up an offer to play baseball at UCLA to accept the Nationals’ offer of $2.925 million and lean on their experience of working with pitchers following Tommy John surgery. Within 11 months of having the ligament in his right elbow replaced, he was back on a mound in a game. He made eight starts for the Nats’ GCL team and posted a 2.78 ERA. He was promoted to Auburn, the Nationals’ short-season Class A affiliate, and punched up a 0.64 ERA over 14 innings.

The biggest weakness on Giolito’s résumé is experience. He has thrown only 382 / 3 innings in the minor leagues. The Nationals want him to continue to improve the command of his biting, mid-80s curveball. (“The potential is there for it to be a plus pitch,” Scialabba said.) His change-up has become a weapon since his elbow operation.

“It’s just one of those weird, quirky things that happens for some guys that get surgery,” Giolito said. “I know sometimes a pitch will feel different.

Giolito’s potential major league arrival date, with an accelerated development program, could be in two years. He is likely to begin this minor league season at Class A Hagerstown and perhaps ending at Class A Potomac. His workload will be limited this season, given his history. And perhaps, the following year, at 21, Giolito could be a contender for a September call-up if he develops as most expect.

“I just want to become a better pitcher and throw more innings and have more experience,” Giolito said. “As far as where I want to be, that’s not something that’s in my control, really. I can just be the best pitcher I can be and hope for the best.”

The Nationals’ front office and coaches rave about Giolito. Manager Matt Williams, who has received great reports on the young pitcher, is slated to see Giolito for the first time on Wednesday in a bullpen session on the minor league side. “I’m excited to see him throw,” he said.

While on a rehab stint in Florida, Ryan Mattheus tweeted about Giolito’s standout stuff. Christian Garcia, another hard-throwing right-hander who also underwent Tommy John surgery in the past, praises Giolito. On a rehab assignment, Garcia overlapped with Giolito at Auburn. “Probably one of the most electric I’ve ever seen anybody throw the ball,” Garcia said.

“He’s mature,” he added. “He works real hard. He’s professional. He makes sure to do his arm exercises, his running. I was really impressed with him. I’ve been around first-round picks and you don’t see them so humble as he is. I was shocked how humble he is and how hard-working he is. He’s got a really bright future.”