She's the one who took Johnson to his first Major League game at Jack Murphy Stadium in San Diego, and she's the one who helped him get an early feel for big league players. She died of cancer, which makes those pink bats even more significant for Johnson.
Now an outfielder with the Cubs, Johnson, 35, said he couldn't remember the first time his grandmother took him to a game, but he can recall the experience.
"I remember going up to the seats and down the first-base line, like up in the loge level at old Jack Murphy Stadium," Johnson said of the Padres' former home field. "I'd leave my seat for batting practice and go out and try to catch fly balls, and then I'd meet my grandmother back up in the seats."
The Padres often had photo days when fans were allowed on the field to pose for pictures with the players and get autographs. Betty made sure her grandson could take advantage of the opportunity and interact with the players.
"Stuff like that was pretty cool for me, to be exposed to Major League Baseball players at a young age," he said. "The more you're exposed to them and the more you're around them, you realize the dream's not as far off as you think, and they're normal people. I think that gave me some confidence that I could develop into a big leaguer."
Johnson started playing baseball as soon as he could, beginning with T-ball. It's all he wanted to do.
"I loved the game, and I'd go there and watch the game," he said. "Back then they didn't have all the stuff throughout the park that kids could do. It's more distracting for kids these days. Back then, it was sit with grandma and watch the whole game."
Johnson's family rented the house next door for Betty after she was diagnosed. But cancer couldn't take baseball away from her. If they couldn't get to Padres games, they'd watch Minor League baseball.
"I was probably a handful, too, so that's why she'd take me to games every once in a while," Johnson said. "She probably just liked to go with her friend, and they'd sit there and watch the game and keep score. She really loved the game of baseball, and when she got sick, which was my junior or senior year in high school, she moved down to Temecula, where we were, and the [Minor League] Lake Elsinore Storm opened up there."
Betty didn't have to play catch with her grandson because Johnson's father did that (with mom chipping in if needed), but she played a huge role in his baseball life.
"Obviously, my dad is big into sports and he was a huge piece of that puzzle," Johnson said. "But my grandma was big in getting me around Major League players and seeing how they work. In the end, that's where I wanted to always play. That helped me out a lot."
She passed away when he was a sophomore at Cal State Fullerton, which was 1997. She never got to see Johnson play in a big league ballpark. He was drafted by the Blue Jays two years later in 1999.
Now, Johnson has his hands full with son Tyce and new daughter Jordan, who was born in April. Betty would probably tell his wife, Taryn, how much young Tyce is like his dad.
"He's definitely a handful," Johnson said of Tyce. "My wife is always trying to do something to burn his energy. Every time I call, they're somewhere, like the zoo or museum. My daughter just lays there and sleeps."
Johnson was a handful, too.
"Tyce will never sit longer than 30 seconds," Johnson said. "That's kind of how I was. I'm enjoying that time now. I know if he's anything like me, you get to that age, and he wants to jump ship and leave town. That's probably how he'll be with me. I've got to enjoy the time now before he wants no part of me."
That's unlikely. Tyce is a regular at Wrigley Field, hanging out with the players during pregame stretch time.
"I loved the game and loved to watch the game," Johnson said. "My son's the same way. He just loves baseball. I'm like, 'Don't you want to play hockey?' Baseball, there's so many steps, there's the Minor Leagues and then the big leagues.
"My wife tells him when he gets older he can play baseball in a league," Johnson said. "He tells her, 'I'm older. I'm ready.'"
Johnson probably told Betty he was ready for the big leagues, too. On Mother's Day, he'll use a pink bat in her honor, and in honor of all other cancer victims.
"I think most everybody in this clubhouse has been affected in some way," Johnson said. "You definitely think about that for sure. [Betty] fought for a few years and lived longer than anyone thought she would. It was really good to have her around."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter@CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.