The Chicago Cubs designated beleaguered relief pitcher Carlos Marmol for assignment, likely ending Marmol's time with the only team he's played for since entering the big leagues in 2006.

"This is probably the best thing for both Carlos and the Cubs," Marmol's agent, Paul Kinzer, told ESPNChicago.com's Bruce Levine. "But Carlos hates leaving Chicago. He's loved his time there, having been in the organization his entire career.

"I had another player who was designated for assignment a couple years ago, and that was Edwin Encarnacion, and now he's an MVP candidate."

Cubs general manager Jed Hoyer said the Cubs gave up long ago on being able to trade Marmol.

"We realized maybe in August last year that we would never be able to trade him," Hoyer said. "He had a really good second half last year on paper and no one really bid at the deadline. We never really had any offers except for someone else's undesirable contract."

The Cubs also announced the suspension of Ian Stewart was settled and upheld, and he was unconditionally released.

The 30-year-old Marmol went 2-4 with a 5.86 ERA in 31 relief appearances this season. Marmol has struggled for parts of the past three seasons. He struck out 32 and walked 21 in 27 2/3 innings this season. He had 10 blown saves with a 4.01 ERA in 2011 and has lost his closer role on several occasions.

"He had struggles that frustrated people at the end of a game," Hoyer said. "We held out on this move for a long time. Partially because of the salary and that he was providing solid innings. The decision came down to that he had become a distraction. Every time he threw two balls to the first hitter, he was getting booed. It became difficult for his teammates because it had become a bit of a sideshow mentality to it. We just felt it was the right time."

"God gives us the opportunity, and he can take it away; that's the way the things are. This is only business," Marmol said to Enrique Rojas of ESPNdeportes.com via phone from Milwaukee. "You never expect this kind of news. I believe that fans were getting a little strong to me. I think it was time to move and try a new beginning."