The mentor is back, and the student is gone: The Chicago Cubs brought Carlos Marmol back from his minor league rehab stint, sending rookie Rafael Dolis down to Triple-A Iowa work on his control. Marmol mentored Dolis, who replaced him as the Cubs closer but eventually fell victim to the same problems that knocked Marmol out of the role in the first place. "Hopefully it's not very long," manager Dale Sveum said of the Dolis's demotion. "It's not a demotion as much as it's going down there and getting right and getting back here pretty soon.