"We brought him in a stroller to a Little League field called Linda Vista, and he really took his first steps there," said his mother, Rocio.
Mendoza's father, Alfredo, smiled and nodded. Now, some 28 years later, his son is making strides as a starting pitcher for the Kansas City Royals.
The big guy with the giant smile and flowing brown locks is having the best season of his career. A sinkerballer, he prospers when he keeps his pitches down and induces ground balls.
"I just concentrate on keeping the games close and giving my team a chance to win. I know I can do a better job, but sometimes I try to do too much. When I'm consistent and can keep the ball down, I have good results," Mendoza said. "The season has been pretty good, but I wish the numbers could be better. I think I've pitched better than the numbers show."
Mendoza will take a 7-9 record and a 4.50 ERA, lowest by any rotation member for the full season, into his Wednesday night start against the Chicago White Sox. His parents, in Kansas City for a late-season visit, will be there.
It's been a long haul since Mendoza signed with the Boston Red Sox in 2000 when he was 16. Born in Veracruz, he was 3 months old when his parents moved to Mexico City, where his father worked for Pemex, the giant state-owned petroleum company.
Alfredo Mendoza, a chemical engineer, and wife Rocio, a hospital biopharmacologist, raised their three sons, Alfredo, David and Luis, comfortably in North Mexico City.
Sports and the outdoors was a big part of the boys' lives --- baseball, swimming, basketball, karate, bike riding, mountain climbing, even American football. They seemed to be into everything all the time.
"I used to tell my husband, 'Hey, give them a break,' " Rocio said through a translator.
A former amateur shortstop, Alfredo coached his sons in baseball. As the youngest, Luis was left out when his older brothers went onto the field.
"He used to cry at the fence because he wanted to be on the field with his daddy coaching him, but he was too little," Rocio said.
Soon, however, Luis got onto the field and his interest in baseball grew.
"He was so smart for his age," his mother said. "We would take him to see the Tigers or the Red Devils in Mexico City. When he was 4 years old, he'd sit on his daddy's lap asking him questions -- 'Daddy, was that an out? Was that a single?' And people around them couldn't believe that this little boy was asking all these questions about baseball. They were kind of amazed at his knowledge."
When little Luis became old enough to be on teams, he was a good-hitting shortstop and third baseman, but his father never thought he'd be a pitcher. The coaches had him pitch an inning or two when was 9 or 10 and he was wild.
"I hit a boy in the face, so I didn't pitch again for about four years, until I was 14 years old," Mendoza said.
But he got so good he was soon playing on teams in national tournaments that drew scouts from the Major Leagues.
"In the nationals when he was 15, he was pitching against a team from Sonora and there were a lot of scouts there, not looking at him but at a shortstop -- Luis Cruz from Sonora, who is now with the Dodgers," his father recalled. "After a few pitches, the scouts liked what they saw, because they immediately got out their radar guns. His velocity was high, his arm was loose."
After the game, the scouts sought out Alfredo Mendoza.
"Your boy can make it," they told him.
After that came recruiting by teams in the United States and Mexico. Alfredo and Rocio were taken to dinner. Offers were floated. One Mexican team actually piled hard cash on the table. However, Luis' parents, who went to the University of Veracruz, were adamant -- they wanted him to get an education. He would finish high school and, if possible, get a scholarship to college.
One scout, Boston's Lee Sigman, remained patient. Mendoza completed high school and his parents were taking another look.
"Even though we insisted that school was first, we started bending a bit over the offers, because Luis wanted to play baseball," Alfredo said. "So we started looking at the upside of baseball. We could see that if he went to the United States, he could learn another language and be bilingual."
Rocio added: "Baseball was part of Luisito's life and we liked the discipline, and his father and uncles had played baseball and it was a family affair."
Mendoza signed with the Red Sox for $65,000, and before long, he found himself in Fort Myers, Fla., where he first found it necessary to speak English.
"It was the first time I traveled for that long, I'd never been away from home," he said. "But more than that, it was a different culture, a different food and a different language."
The Red Sox, like many Major League clubs, have English classes for their Hispanic players, but it's the day-to-day life where they really learn. An older roommate Mendoza had in Class A ball at Augusta, Ga., in 2003 helped.
"Sometimes we were shy about trying to speak English because they might make fun of us, but this guy said, 'OK, you want to eat? You've got to order your food or you're not going to eat.' So that was a good thing," Mendoza said. "We were calling Domino's Pizza at that time and it was like, 'OK, you want a pizza? You call. I'll tell you what to say.' Then I'd go the mall and I remember the first drink I ordered was at Starbucks, and I was shy and scared if they would understand or not. But that helped me a lot."
Today, Mendoza speaks fluent English. And, unless he's doing serious stuff like pitching, with a huge smile.
"We believe that Luis is always a happy camper because of the way he was raised," his father said. "My three children were always happy, because they had the liberty to do things outdoors and my wife and I always went with them and did things as a family."
His mother believes it's in his DNA.
"He was born with that happy, outgoing personality," she said.
That's undoubtedly what helped him win the heart of his wife Monica. In 2005, she lived in Navojoa, where Mendoza happened to be playing winter ball. He also happened to make friends with Glen Marquez, a guy who helped the team mascot with his routines.
"I struck up a good friendship with him, but I didn't know he had a sister," Mendoza said.
The sister was Monica, and they met at a family party. They became just friends at first but stayed in touch and, three years later, started dating and eventually married. Now they make their home in the Mexican city of Hermosillo.
Mendoza is among more than a dozen Mexican-born players now in the Major Leagues.
"We're proud we can raise the flag of Mexico by being in the big leagues," he said.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.