I met Anthony Rizzo, who has just led the Chicago Cubs to the playoffs, in Mesa, Arizona, in 2012. We were at spring training for the Cubs. He was a first baseman who had been traded to the team from the San Diego Padres, and I was a second baseman who had been claimed off waivers from the Oakland Athletics. I had yet to make it to the majors; he had had a brief stint, a cup of coffee, with San Diego, where he struggled and was eventually demoted. We both knew we would likely start the season in Triple A, but we wanted to make good first impressions with our new team. When we discovered that we grew up forty minutes from each other—he in Parkland, Florida, me in Miami—we reminisced about the beach, and joked that in Arizona, your only chance of finding water was to take a bat and smash open a cactus.

When we got to Triple A, we sublet neighboring apartments in downtown Des Moines, our team’s home city. About a week into the season, he heard that I played piano; once, in some hotel lobby on the road, he dared me to play. I did, and when we got back to Des Moines, he sent me a text asking me to come to his place. I found him sitting on a chair, butchering some pop song on a newly purchased keyboard. He wanted to get it just right in order to impress his girlfriend when she visited. “Guy, teach me how to play this,” he said, “I need to learn this song in two days.” I laughed. The keys weren’t weighted, there were no pedals, and the keyboard didn’t have enough octaves to play the song. It was like stepping up to the plate with a Wiffle ball bat. He had never played the piano, but his instincts were good, and he wouldn’t move on to another measure until he could play the previous one. He spent hours practicing, and would occasionally call me, asking about notes and rhythm—how to do it like the pros, essentially. In a couple of days, he even managed to turn out something on the low end of decent.

This, of course, was not unlike the way he worked on his craft as a ballplayer. I have watched him, ground ball after ground ball, become one of the best defenders in the game. He’s better known for his power at the plate, but his hands are as smooth as a shortstop’s, and I know he takes special pride in that, because fielding always lingers in the shadow of hitting, never receiving as much credit but always deserving more.

My own defense, on the other hand, was a question mark. Was I quick enough? Versatile enough? Could I make the routine play consistently? I put so much importance on every play. Early in that 2012 season, in Triple A, I dove for a ball between first and second, and it kicked off the heel of my glove. The scorekeeper marked it as an error. I was furious, in part because I should’ve made the play, but also because I didn’t think I deserved the error. When the game ended, our manager called me into his office and told me that the error was removed—Rizzo had spoken to the scorekeeper and changed his mind. From then on, we were brothers.

I made my major-league debut on May 7, 2012. Before I left Des Moines, I swung by Rizzo’s place to share the news; he gave me a hug and said that he never wanted to see me in Triple A again. While I was in the majors, all anyone talked about was when the Cubs would promote Rizzo. His .342 batting average, twenty-three home runs, and sixty-two R.B.I.s—in just seventy games—forced the issue, and, on June 26th, he got the call. In order to make room on the roster, someone had to get demoted. That someone was me. Rizzo arrived in Chicago and took over the lease of my apartment. He pulled into the driveway as I was loading my car with luggage. He rolled down his window and smiled. “What are they thinking—you weren’t even doing that good,” I joked. He helped me with my bags and looked like he was going to apologize before I told him not to dare. Rizzo was named the Rookie of the Month that July—insuring, just as he had hoped, that he would never see me in Triple A again.

When I was recalled to the majors, a month later, Rizzo was already one of the team’s leaders. On the few days that I started at second base, he would heckle me. Mid pop fly, he’d warn me not to run into a tree, or trip over a computer; when a batter hit a towering fly ball, he’d ask if it was too high for me to catch, if I needed assistance. This might seem odd, or aggressive, but it was just a way to keep a teammate loose—the kind of thing that helped us play better. Rizzo was good at that.

One day, the morning after a long night game, I found him in the training room. We had a game that afternoon, and he was asking the trainer if he should be worried about feeling fatigued. This struck me as funny—it would be abnormal to wake up and not feel tired. (They say you are only at a hundred per cent on the first day of spring training. They’re right.) When Rizzo left, I joked with the trainer that Rizzo was being a hypochondriac. That’s when I learned that, in the spring of 2008, Rizzo had been diagnosed with Hodgkin’s lymphoma, and he’d missed the rest of that season to undergo chemotherapy.

Despite missing that year, he still made it to the majors by the age of twenty-one. He has since become an All-Star. I left baseball after the 2012 season, and now I mostly see him on TV. He’s had another great year at the plate, leading the Cubs in home runs, and stealing more bases and scoring more runs than all but one of his teammates. Defensively, he’s been gold, as usual. He’s not just making the routine plays, either: during a game in mid-August, he climbed onto a tarp, snagged a ball headed for the seats, and fell into the crowd. Afterward, the fans around him—including one wearing a Rizzo jersey—patted him on the back. The Cubs won the game in extra innings.

A few weeks ago, I returned to Chicago for the first time since 2012. I visited Rizzo for a few minutes at his apartment, while he ate lunch with his parents. As I left, he asked if I was going to swing by the clubhouse. “No, thanks,” I said. I couldn’t imagine stepping into that space. Nothing extraordinary happens there, but it’s sacred nonetheless. I’m happy, like that guy in the stands with the Rizzo jersey, to cheer from a distance, and pat him on the back when I get a chance.