(CBS) Former Cubs infielder Starlin Castro has thanked the franchise and its fans in a heartfelt first-person piece posted to The Players’ Tribune.

The Cubs traded the three-time All-Star Castro to the Yankees for right-hander Adam Warren in early December, in part because of an infield talent crunch and in part because of his inconsistencies. While admitting his six-year career in Chicago was “full of ups and downs,” the 25-year-old Castro expressed nothing but thanks for those in the organization.

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“The Cubs fans were always so good to me, and I will never be able to thank them enough,” Castro wrote. “When I got to Chicago, I was just a kid, trying to figure things out at a new job in a new city. When you’re new, you want to be approved of, and you want to belong. Those first big cheers I got at Wrigley are something that I will never forget. They helped me feel like I was doing something right — and they helped me feel like I was home.

“To the Cubs organization: I’d like to thank you — for everything. You gave me an opportunity, you believed in me and you were always honest with me. You didn’t just help me grow as a player; you helped me become an adult.”

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Castro called it a “struggle” to get replaced as the everyday shortstop by rookie Addison Russell in early August but was proud of how he handled the demotion.

“I also took pride in the fact that I was not going to be one of those players who lost his spot and then brought the team down with him,” Castro wrote. “I knew that I had been taught — by veterans like Alfonso, and other great leaders in the Cubs organization — to be better than that.”

Castro is expected to be the Yankees’ everyday second baseman. He hit .265 last year with 11 home runs and 69 RBIs in 151 games. He’s a career .281 hitter.

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Read Castro’s full first-person piece here.