Starlin Castro made a souvenir out of an 89 mph pitch from Ian Kennedy in the first inning, hitting the ball to the fans in the right-centerfield seats beyond the auxiliary scoreboard. The Yankees’ second baseman crossed the plate, clapped his hands and was welcomed in the dugout for his one-swing, four-base feat.

Just a few hours before this game against the Royals Thursday night at Yankee Stadium, Brian Cashman was standing by that dugout and talking about Castro. And the general manager was applauding the work by one of his prize offseason acquisitions, who was moved from short to second last August while with the Cubs.

“I had a lot of people in my ear that this is a high-ceiling player that’s still young, still developing,” Cashman said. “The transition to second base, how he transitioned over there — he could be a real nice, controllable young piece for us. So he’s come in here with a great attitude and obviously a good performance to boot.”

Castro’s latest performance — 2-for-4, including the solo homer and an RBI single, plus a glittering defensive play on a grounder — helped the Yankees claim a series-closing 7-3 win, their third in the four games against Kansas City and fifth in seven games on the homestand.

“I think it’s a great opportunity for me to be a part of this team,” Castro said, “especially now that we’ve started winning.”

The price tag for the Yankees to fill their lingering hole at a position that Robinson Cano manned so smoothly from 2005 through 2013 was a versatile pitcher in Adam Warren and infielder Brendan Ryan.

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It has worked out so far for the Yankees.

Castro leads the Yankees with 36 hits. The 26-year-old three-time All-Star, who spent six seasons with Chicago, is batting .300 with eight doubles, a triple, four homers and 14 RBIs in 32 games. He’s batting .360 over a seven-game hitting streak, the longest by a Yankees second baseman since Cano had the same streak in September of 2013.

And Castro has made only one error.

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“He’s contributed huge for us,” Joe Girardi said. “He’s been really consistent, probably our most consistent hitter in the lineup. He’s really learning how to play second base. He’s worked really, really hard . . . I applaud him for the way he’s went about his business.”

When he delivered his 1,000th hit on April 15 against Cano’s Mariners in the Bronx, Castro became the seventh-youngest player that debuted in the last 50 years to hit that milestone.

Yankee Stadium has been especially user-friendly for him. His home work includes a .348 average with six doubles, three homers and 11 RBIs in 18 games.

“I feel good not only here,” Castro said. “I feel good at the plate no matter what place it is. But there’s nothing better like home. I think this is a really good park to hit. I just do an adjustment and hit it pretty good here.”