The Miami Marlins appear intent on pursuing a starting pitching upgrade this winter, as the position is "high on Miami's shopping list this offseason", according to MLB.com's Joe Frisaro. The Marlins seem set on adding versatility to their 40-man roster, which could lead to some current starters moving to the bullpen, opening the door for new faces in the rotation.
Though both seem to be staying in the rotation as of now, Nathan Eovaldi and Tom Koehler are candidates to potentially move to the bullpen next season, per Frisaro. Add in Jose Fernandez likely being sidelined until at least mid-season, and the Marlins' rotation could enter next season looking almost entirely different than it did at the beginning of 2014.
RIght now, Handerson Alvarez and Jarred Cosart appear to be the only locks for the rotation, though I would put money on Eovaldi and Koehler sticking as starters. That still leaves the fifth starter spot, which could be filled via a number of in-house options including Andrew Heaney, Justin Nicolino, and Anthony DeSclafani. Once Fernandez returns, the Marlins could easily have one of the brightest young rotations in baseball.
Frisaro also mentions a number of other candidates to switch positions. Outfielder Christian Yelich could see time at first, though it would appear to be a longshot. Second baseman Derek Dietrich may move to first base or left field due to lackluster defensive abilities at the keystone, though it's doubtful that his bat could play at first. Catcher Rob Brantly could also add corner infield responsibilities, as Jarrod Saltalamacchia is entrenched as Miami's starting catcher for at least the next two seasons.