Mancini opted out of his minor-league contract with the Marlins on Saturday, Jordan McPherson of the Miami Herald reports.
Mancini's decision suggests he was not going to make Miami's Opening Day roster, so he will now try his luck on the open market. Mancini slashed .234/.299/.336 with 28 RBI across 261 plate appearances with the Cubs last season and may still be able to find a big-league opportunity with a team in search of 1B/OF depth.