(CBS) After a splendid start to the season in which he hit .325 with a .349 on-base percentage in April, Cubs shortstop has cooled off. He’s hitting .214 with a .250 on-base percentage in May, leading some to wonder what’s wrong with his game.

Part of the answer is Castro’s pulling the ball too much, Cubs manager Joe Maddon said, but the man in charge isn’t too worked up.

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“He hit the ball well twice to center field (on Monday),” Maddon said in an interview on the Spiegel and Goff Show on Tuesday. “The biggest problem is the rollover ground ball to the pull side, and he knows that. He’s working on getting away from that. Be careful. This guy’s a .300 hitter. For his entire career, he can hit. Sometimes you go through these moments. Primarily, like I said, it’s more body, not enough hands. ‘I’m trying to pull the ball too much. I’m trying to do too much.’ We’re talking to him daily to try and get him away from that. In Arizona a couple days ago, he had that base hit down the right-field line. He had a line drive to right central. Yesterday, two balls hit to center field. So we’re working on that. It’s going to continue to get better. So just be patient with it.”

On a more positive note for Cubs fans, Maddon also spoke glowingly of 22-year-old catching prospect Kyle Schwarber, who’s hitting .305 with 10 homers and 26 RBIs in 41 games at Double-A Tennessee. Maddon hasn’t shut the door on the notion that Schwarber could be called up late in the season to help out the Cubs, though there are many young players in the organization who could get that nod.

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“I like him,” Maddon said. “I got to meet him in spring training. I got to watch him — a unique young man when it comes to an at-bat. He works at at-bat in a very mature manner. You don’t see it often. You don’t see the combination of plate discipline and the ability to put the bat on the ball and power at that age. It’s just unique, so that’s what I was referencing. We have a lot of young guys that I think may have that opportunity before this season is over, to come up and help us out.

“The big thing with him is, developmentally-speaking, he’s got some ways to go as a receiver, as a catcher. We’re working on that diligently and so is he. He in spring training was relentless on a daily basis, getting more information, extra work. It was really fun to watch. This guy’s going to make an impact on us in the future. I don’t know exactly when, but he’s having a really, really good minor league season. We’re all looking forward to him getting here at some point.”

Listen to Maddon’s full interview below. He also addresses how the Cubs have handled the various-and-sometimes hectic start times to games, Nationals star Bryce Harper and much more.

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