After spending the past six seasons in the Korean Baseball Organization, Casey Kelly returned to a Triple-A mound in the United States on Sunday and found some things had changed.

But at least one thing was very familiar.

"It's a little bit of an adjustment. There are new rules, there's the pitch clock, the ball's a little different," Kelly said. "Honestly, though, the coach that knows me the best was my manager today."

Kelly arrived back in the U.S. on Monday, and two days later, he signed with Cincinnati as a Minor League free agent and was assigned to Triple-A Louisville. The Reds affiliate just happens to be managed by Pat Kelly, Casey's father.

The elder Kelly became the seventh manager in history to amass 2,000 wins in Minor League Baseball last month. The first of those victories came with the Charleston Rainbows in 1986 -- three years before Casey was born. His most recent "W" at the helm -- the Bats' 4-3 walk-off over the Charlotte Knights (White Sox) on Sunday at Slugger Field -- was started by Casey, now 34 years old and with 15 years of professional experience under his belt.

"It's very surreal," Pat Kelly admitted. "It's funny -- I was nervous. You always want your children to do well and have success. You're usually rooting for them from the stands, or maybe on TV or video. This was a lot different."

And the father-son/manager-player relationship does put the Kellys in a small club. Even in the long, well-documented history of the American and National Leagues, there have been just seven instances of a father managing his son, per Elias Sports Bureau:

Bruce Bochy (Brett, 2014-15 Giants)
Felipe Alou (Moises, 1992-96 Expos and 2005-06 Giants)
Bob Boone (Aaron, 2001-03 Reds)
Hal McRae (Brian, 1991-94 Royals)
Cal Ripken Sr. (Cal, 1985, '87-88, and Billy, 1987-88 Orioles)
Yogi Berra (Dale, 1985 Yankees)
Connie Mack (Earle, 1910-11, '14 A's)

Kelly had managed his other son -- reliever Chris Kelly -- during a Winter Ball stint in Puerto Rico in 2008-09. That experience did little to quell Sunday's butterflies, which were exacerbated by his son having turned up on his mound in Louisville after spending years on the other side of the planet.

Casey, on the other hand, was too overwhelmed with wonder to be nervous.

"It's one of the coolest things that could have happened. I just soaked it in," he said. "Once you're out on the field and the game starts going, obviously it's business as usual."

Limited to 50 pitches because he hadn't thrown in a game in a few weeks, he allowed one hit and walked three over three scoreless innings.

Casey Kelly was drafted by the Red Sox as a high school shortstop with the No. 30 overall pick of the 2008 Draft. He became a two-way player in the Boston farm in 2009 and converted to strictly pitching the next year. That winter, he was traded to the Padres in the blockbuster that brought Adrian Gonzalez to Fenway Park. He's since pitched for San Diego, Atlanta and San Francisco in the Majors as well as in the Cubs' system and Dominican Winter Ball.

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Casey's time in Korea -- beginning in 2019 and involving a postseason run with the LG Twins every year and a championship in 2023 -- cemented him as one of the most beloved foreign players in KBO history. In 163 starts, he was 73-46 with a 3.25 ERA. When he was released in late July, he had interest from teams elsewhere in Asia as well as a few MLB organizations.

"The last couple years," Pat said, "I've made some jokes like, 'Before I retire you've got to come pitch for me.' I didn't expect for that to happen this year."

The elder Kelly had gotten used to getting up at 5 a.m. to watch his son's KBO starts, having missed only one outing during the six-year tenure. But even though both Kellys will continue to pull for the LG Twins (currently in second place), they've already developed a routine that wasn't possible before this week.

"He's got a son who's almost 3 years old, C.J., and he's been in my office every day after the game," Pat said. "After him being halfway across the world the last three years, that part of it is nice."

That, for Casey, brings things full circle.

"That was me when I was 3 years old -- playing in the clubhouse after games and before games," he said. "Me and my brother were always around, so to sit back and see him play with C.J. in his office ... it's a once in a lifetime experience."