I think you should definitely look for an upgrade at OF to take over Moises Alou's spot, but I'm not sure about your need for another closer. I would look at trading Rapheal Soriano to help you get some more juice at OF-- he is 3rd in line for the Braves' closing job, and although good, will not get many save chances behind Wickman AND Gonzales in my opinion.
Zumaya, on the other hand, stands an excellent chance of being a closer SOMEWHERE this season.
At 3B, you seem to have two excellent backups, or two very weak starters. An upgrade there is a posibility, but not a necessity, as one of those two will probably stand to have a good season.