(CBS) Starlin Castro has improved defensively at shortstop this season, but he continues to have mental lapses.

The latest came Monday, when Castro forgot how many outs there were and failed to throw the ball to first base to complete a double play with the bases loaded. Manager Dale Sveum was immediately shown on television shaking his head, so it wasn’t a surprise when he delivered an ultimatum to his shortstop after the game.

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“It’s the last straw,” Sveum said. “He better start getting his head in the game, period.”

Despite elite skill, Castro continues to make baserunning and fielding mistakes and is earning a bad reputation.

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“It’s not acceptable,” Sveum said. “These things have to stop happening, or we’re just going to stop playing him. These kind of things are things my son does in high school.”

For what it’s worth, Castro was very apologetic after the Cubs were swept by the Giants.

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“It’s very embarrassing,” the shortstop said. “This can’t happen. I apologize to my team because that kind of thing is not supposed to happen.”