I have thought about this for the better part of five to ten seconds and the only thing I came up with was that the Marlins are planning to move Anibal Sanchez off the 60-day DL and back onto the 40-man roster.
Naturally, this is just a guess and maybe you can come up with something better. But if the Marlins were looking to add an infielder, you know, one that could play shortstop and other positions, Andy would still be on the roster. Or if the Marlins were looking to add an outfielder, you know, one that is a legitimate player of the field, the Marlins wouldn't have had to make this move. Carroll is already on the 40-man. Which leads me to believe that the club thinks Anibal is very close to ready.
I may be off by a mile on this one.