(CBS) The Chicago Cubs have designed often-erratic pitcher Carlos Marmol for assignment.

The 30-year-old Marmol went 2-4 with two saves and a 5.86 ERA in 31 relief appearances this season. He struck out 32 and walked 21 batters in 27.2 innings pitched, an average of 10.4 strikeouts and 6.8 walks per nine innings.

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Cubs manager Dale Sveum shifted Marmol in and out of the closer role periodically throughout the season.

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In eight seasons with the Cubs, Marmol, who is earning $9.8 million this season, went 23-32 with a 3.50 ERA in 483 appearances with the Cubs, 470 of the outings in relief.

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The Cubs also released third baseman Ian Stewart, whose suspension for making derogatory comments about the organization on Twitter was upheld.