The Marlins are going with a closer by committee, at least for the short term.
The ones who are in the running are the usual suspects: Owens, Lindstrom, Gregg with Messenger also included. Tankersley will be added to the mix once he is up to speed.
I'm not a big fan of closer by committee since it generally means you don't have anyone who is actually good enough to handle the role on a full-time basis. What also confounds the idea is that pitchers like defined roles, they aren't faucets you can just turn on and turn off. Therefore it rarely works.
That said, the Marlins may be able to pull this off. The team has a school (fish term) of potential closers, who aren't far removed from spring training where they were used to trying out different roles every other day or so.
The closer-of-the-day selection committee is already in place.
The Marlins can probably get away with this for awhile but I think eventually the team has to define the roles in the bullpen. But it isn't critical right now, since the learning of the personnel is still in progress.