The dads and sons were packed onto the team's charter flight and into the hotel and to the ballpark.
It was the brainstorm of the Royals' senior director of travel, Jeff Davenport, who borrowed the idea from NHL teams. He bounced the idea off general manager Dayton Moore and manager Ned Yost.
"It took them about five seconds to say yes," Davenport said.
No one is quite sure, but it could be a first for a Major League Baseball team.
The dads came from near and far for the trip. Luis Mendoza's father, Alfredo, came from Mexico. Bruce Chen's pop, Jose, came from Panama. Gordon came from Lincoln, Neb., Wade Davis' dad, Ben, drove from Sebring, Fla., to meet him here.
Robert Johnson, father of infielder Elliot Johnson, flew in from Indiana.
"Elliot told me about it and I had to call him back three times to make sure I got this story right -- I said, 'You've got to be kidding me. All I have to do is get to Kansas City and they're going to put me on a plane and fly me along with you and not charge me anything? And I'm going to get in a hotel and eat with you guys and hang out with you?'"
Well, it was all true and the guys are having a blast, including Alfredo Mendoza.
"He's enjoying this and taking pictures everywhere to show my mom and his family back home," Mendoza said. "Knowing my dad and how crazy he is for baseball, this is unbelievable. Baseball is his life."
Same thing for Robert Johnson, who had five sons including four that became pro players. Only Elliot made it to the Majors.
"I'm a baseball guy, baseball was my life, my dad's life -- and we didn't make it," Robert Johnson said. "My dad's got a grandson in the big leagues and doing this is just like a lifetime dream."
Coaches George Brett and Doug Henry brought their sons along.
"It's a great idea. I wish my father was still alive, but I have the next best thing: I got to bring one of my sons, so it was great," Brett said. "I just got his Father's Day card: 'Thanks for taking me on the trip.' So, it was pretty cool."
Jackson Brett wears a uniform and hangs around the clubhouse.
"This is unbelievable. I love it," Brett, 20, said. "It's a dream come true. It's my first trip ever. It's awesome."
Jackson Brett went out to center field at Tropicana Field and visited the water tank where Tampa Bay's namesakes are swimming.
"I went to pet the rays one day and that's really a cool thing they do here," he said.
For guys like Chen, it's a chance to say thanks to a father who helped them learn baseball as they were growing up.
"When I was little, my dad taught me about baseball. He always practiced with me and he'd throw batting practice for me or catch for me. He took me to a lot of my games," Chen said.
"Now, years later, I'm able to say, 'Dad, come on the trip. This is how we travel.' I feel good that the team has given my opportunity to give my dad this experience of being here in the big leagues. To visit and be on the field for the first time ever, being here at batting practice, see how everything is run."
Robert Johnson was one of those dads and this trip afforded him an unexpected fringe benefit.
"I got into an argument with George Brett last night, if you can imagine that, over Elliot's hitting," Johnson said.
Who knows more about hitting -- George Brett or Robert Johnson?
"I'm sure he does," Johnson said with a grin, "but I know a lot about hitting."
He and the other fathers got to sit in the dugout during pregame practice and walk around on the field at Tampa Bay.
"For a baseball guy that didn't make it, this is hallowed ground," Johnson said.
Note to the training staff: Get out the liniment. The dads will be taking batting practice on Monday in Cleveland.