After trading Carlos Zambrano to the Miami Marlins on Thursday, Chicago Cubs president of baseball operations Theo Epstein said his first inclination after talking to team players and personnel was to trade the disgruntled pitcher.

"I talked to enough [players] in order to get an understanding of the history here," Epstein said. "This isn't a decision that players will make. But I think if you don't listen to what happens in the clubhouse then you can't develop a proper understanding of it."

The transaction requires the Cubs to pay $15 million of the $18 million owed Zambrano in 2012, a source said. Zambrano had a $19 million vesting option for 2013 if he finished in the top four in Cy Young Award voting, but he waived that and will receive a $100,000 bonus if he is voted the comeback player of the year.

Zambrano also waived his no-trade clause, and the deal hinged on the Cubs agreeing to pay back $2.4 million of the $3 million Zambrano lost when he was put on the disqualified list for leaving Atlanta's Turner Field -- and saying he was retiring -- on Aug. 12, the source said.

"I'll just say that the people who have been around the situation over the years heard before there would be change," Epstein said. "They heard before there would be a new attitude, and they have been burned. Physical altercations, deserting the team, that type of thing. The best way to put it is there was a breakdown of trust. It would have been very difficult to re-establish that trust."

The Cubs will receive right-handed pitcher Chris Volstad in return. The former first-round draft pick was 32-39 with a 4.59 ERA in 103 major league appearances, including 102 starts, with the Marlins the past four seasons.

The 6-foot-8, 230-pound Volstad is 25 and a workhorse, having made at least 29 starts in each of the past three seasons.

"We've all been a little bit baffled by some of Chris' inconsistencies," Marlins president of baseball operations Larry Beinfest said.

For Zambrano, the possibility of pitching for friend and former Chicago White Sox manager Ozzie Guillen may have played a role in waiving the no-trade clause.

"Ozzie has a long and close relationship with Carlos," Beinfest said. "We went with Ozzie on this one. The bottom line was Ozzie just really, really felt confident about this deal."

The emotional right-hander had several highly publicized outbursts as a Cub, one being a dugout altercation with former teammate Derrek Lee in 2010 while facing the White Sox that lead to a suspension. After that game, Zambrano had dinner with Guillen, who supported the pitcher.