BOSTON — Yoan Moncada returned Thursday night to face for the first time the team that traded him away.

But if the White Sox second baseman had any wistfulness about leaving the Red Sox in the blockbuster Chris Sale trade in December, he wasn’t letting on.

Before a 9-5 White Sox loss to the Red Sox, Moncada said he was happy to catch up with former teammates and executives at Fenway Park, but he added he hadn’t paid much attention to the American League East leaders this season.

Moncada is too wrapped up in his first few weeks with the rebuilding White Sox, where he faces a very different set of circumstances than he did in Boston.

“I wasn’t expecting to be traded,” Moncada said through a team interpreter. “It was a good opportunity for me. Now I’m with this team and I feel that was the best for me, the best for my career. I’m just glad it happened.”

After missing two games with a bruised leg suffered in an outfield collision Monday, Moncada went 0-for-2 with two walks Thursday. He scored his second run on Nicky Delmonico’s first career homer, a three-run shot off Rick Porcello.

But White Sox right-hander Miguel Gonzalez gave up seven earned runs over 12/3 innings, including two-run homers to Mookie Betts and Rafael Devers, Moncada’s former minor-league teammate.

The White Sox lost for the 20th time in 24 games, a stretch in part driven by the trading last month of seven veterans for a stockpile of prospects the Sox hope eventually will complement Moncada.

When Moncada last played in Boston in September, the Red Sox were in search of a spark for a playoff push. They had him play third base, a position he had manned for just 10 games in the minors.

Moncada started the year in high Class A and had played just 45 games in Double A before his call.

The combination of the quick climb up the ranks, lofty expectations and move away from his natural position at second base made for a difficult transition. He was 4-for-19 with an RBI, a walk and 12 strikeouts in eight games.

“Last year I wasn’t expecting to play in the majors,” Moncada said. “When they told me, I was happy because of course that’s what every ballplayer wants, but I think that I wasn’t ready. (Last year’s move) was really fast for me. Things didn’t go well at that time, and that created a bigger issue.

“This year I know what my role is and know I’m going to be playing every day. Because I have experience from last year, that made me feel more comfortable and I’m more prepared for this opportunity.”

The White Sox kept Moncada at Triple A this season longer than some might have expected, and he said his work on defense at second base over 80 games has been his biggest area of improvement since his time in Boston.

Moncada is 4-for-40 with a double, a triple, homer, six RBIs, eight walks and 17 strikeouts over 13 games.