KANSAS CITY -- If non-drafted free-agent reliever John McMillon some day makes it to the Major Leagues, he might just have the best Royals nickname since Bob “The Hammer” Hamelin.

That’s because McMillon was nicknamed “The Whammer” back in high school in Jasper, Texas.

“I don’t think anyone calls me ‘John’ anymore,” McMillon told MLB.com. “It’s always been ‘Whammer.’”

And this was before anyone knew McMillon could rifle a fastball over 100 mph. McMillon was in Kansas City on Monday for his physical, which he passed, and he agreed to a contract for $20,000 on Tuesday.

For the youngsters out there, “Whammer” is the name of the legendary slugger in the movie The Natural, whom Roy Hobbs [Robert Redford] struck out on three pitches during the movie’s opening.

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McMillon, 22, got that nickname not because of his power fastball. He was a hitter through his sophomore year at Texas Tech and known for prodigious home runs.

As one MLB scout said, “You know, if you ever need someone to win a Home Run Derby, he’s your man.”

Even McMillon admits he was pretty much an all-or-nothing hitter: “I’ve always been a BP hero.”

But eventually McMillon, who even looks like a young Joe Don Baker [the actor who portrayed The Whammer] with his 6-foot-3, 220-pound frame, found his calling as a pitcher. Coaches noticed his strong arm as a catcher and wondered how it would translate to the mound.

It did.

McMillon posted a 1.75 ERA in 24 appearances as a freshman at Texas Tech. He struck out 29 in 25 2/3 innings. But he still had a desire to use his power at the plate, too. In 18 starts as a designated hitter that year, he hit eight home runs, second most on the team.

But McMillon hit just .143 as a sophomore, and eventually the decision was made for him to focus just on pitching.

“There’s a part of me that will always consider myself a hitter, too,” McMillon said. “But to get where I’m going, I need to do it on the mound.”

The coaching staff at Texas Tech also had to decide where best to fit McMillon on the staff. It tried him as a starter, but liked him out of the bullpen, too.

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McMillon will leave his future role up to the Royals’ Minor League development staff.

“I love the high-leverage situations,” he said. “I love coming in and striking guys out with the bases loaded.

“That kind of attitude benefits me. I feel that clutch-time, high-leverage time, game-on-the-line and you need a punch-out, that’s me.”

McMillon, though, disputes the theory that his velo couldn’t be maintained near 100 mph as a starter. He doesn’t feel he has to amp up at all to reach 100 in short stints.

If a Texas legend such as Nolan Ryan can hit 100 throughout the game as a starter, why can’t McMillon, he argues.

“Who says you can’t be another Nolan Ryan?” McMillon said. “I can throw hard throughout a game. I know I can.”

Scouts began noticing McMillon’s arm talent and hitting prowess when he was in high school.

“Everything he did was big,” one rival scout said, with a chuckle. “He was just Texas big. He could throw hard, he could hit the ball a mile. He was a big kid. He was definitely ‘country strong.’”

Tampa Bay drafted McMillon out of high school but he opted to go to Texas Tech.

After his junior season with the Red Raiders, the Tigers took him in the 11th round in 2019. Negotiations broke down and the two sides couldn’t reach a deal. He returned to Texas Tech, and then his world, like everyone else’s, was turned upside down by COVID-19.

Instead of getting a more lucrative deal from the Tigers, he went undrafted in the shortened five-round MLB Draft earlier this month.

But McMillon isn’t looking back. He has no regrets.

“Not everything can be measured fiscally,” he said. “Things happen for a reason. I’m incredibly happy to be a Kansas City Royal. This is where I should be. You’ll see.”