While making a stellar play in an April 10 game in Oakland, Cain hit the outfield wall and injured his left groin. Just three days away from making his debut at his new home ballpark of Kauffman Stadium, Cain would be forced to wait. Little did Cain know that wait would last three months.
But Cain's long wait shouldn't come as too much a surprise. He's always been a late starter. Now 26 years old, Cain didn't start playing baseball until his sophomore year of high school.
Of course, it was for good reason. Cain's mother, Patricia Cain, worked a pair of jobs to support her two children as a single mother. That meant Cain and his older brother Delvin had to come home from school each day and do chores and other things to help their mother around the house.
"She worked two jobs to support me and my brother, so it was more of me and him helping out around the house, just trying to take off as much stress as we could from her," Cain said of his mother. "She's a very hard worker. She's done everything possible to give me things, maybe that she didn't have. She's definitely been there throughout my life and I love her to death."
It meant little time for sports, unless you count some backyard baseball and a love of video games. Eventually, like all kids, Cain had enough of chores. He decided to try out for the baseball team at Madison County (Fla.) High School. He spent his sophomore year on the JV team and he didn't play much on the varsity squad until his senior year.
"My senior year, I started on varsity, and it just kind of went from there," Cain said. "I kind of picked it up and worked hard. I was determined to never sit on the bench. That was the thing about me, I just couldn't settle with sitting on the bench."
He might not have played much at all, though, if it wasn't for the aid of his coach, Barney Myers. With Cain's mother hard at work, he had no way to get from his house to practices and games. Myers picked him up and brought him home, no matter the hour, enabling Cain to keep playing.
"He did a lot of stuff for me," Cain said. "My mom wasn't able to bring me to practice or bring me to the games, so he definitely helped out in that aspect of after the games, no matter how late it was, he would take me home or pick me up before practice. He just did all the little things that I needed to make sure I was able to get on the field and play each and every day. He's a big part of my life, and I've always appreciated the things he's done for me."
Cain eventually earned a scholarship to Tallahassee Community College and was drafted by the Brewers in 2004, a long way to come for a kid who had only started playing a few years prior.
In December 2010, Cain was traded to Kansas City in the deal that sent Zack Greinke to the Brewers. The following offseason, the Royals shipped Melky Cabrera to San Francisco, paving the way for Cain to take over in center field.
"He had come a long way from not ever playing," Patricia said. "People always say, 'I don't believe that he never played baseball.' I say, 'It's the God's honest truth.' He did not play when he was growing up, nothing other than a little baseball field at the house. But it was nothing that he would take serious."
But then came game No. 5. Cain ran down a fly ball, making a great catch and crashing into the wall. Three days later, Cain went to the disabled list with a strained groin. Not even two weeks after that, Cain sustained a second injury, this one to his hip flexor. He was sidelined for months.
Cain was understandably upset with the way things went, but his mom was there for him.
"I was frustrated with the injuries this year," Cain said. "One thing about her is when I'm down, I can definitely give her a call and she always brightens my day up. She was definitely there for me throughout that process, my injuries. It definitely helped, I will say that. Going through injuries is frustrating, but she was there for me, continued to motivate me, keep my head up."
After all the frustration, Cain finally made it back and it came with a bang.
In his first game at Kauffman Stadium, Cain was 3-for-6 with a double, an RBI and three runs scored. And things kept rolling from there. In his first 12 games back from injury, he hit .390 with three doubles, three home runs, seven runs scored and 13 RBIs. His numbers dipped slightly on the Royals' recent road trip, but he's still batting a strong .293 since returning.
Cain still hasn't completely recovered from his injury and his legs were said to be at about 85 percent. The Royals staff wanted to give Cain rest, but his bat was too valuable.
"We've got to come here every day trying to win baseball games, and if his presence in the lineup makes us better, then he needs to run out there and play center field," said Royals outfield coach Doug Sisson. "That's why they've got Advil in the training room."
Taking a cue from his mom and his high school coach, Cain continues to work hard. But there's one goal he hasn't yet achieved. Patricia has never seen her son play in a Major League game, and he hopes to get her to one of his games soon.
"It would be very important for me to see him play, very important because I love him so much," said an emotional Patricia. "It brings tears to my eyes because he has made me so proud."
Vinnie Duber is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.