The Sox are clearly playing the "depth" game at bullpen.
To me, I think this means it will be a big surprise if both Workman and Thornburg are not on the opening day roster, and from there it becomes a matter of time before either are both are either established or released.
With 2 open spots on the 40-man roster, the Sox do have a few internal options they can promote. A lot of the arms the Sox signed might never see Fenway. Who has high hopes for Schlereth or Runzler or Ellington or Tapia? (OK I have mild hopes for Tapia, but they aren't likely to come true.) Before any of them, the other 40-an options include Poyner, Hernandez, Lakins, and Colten "Big Offseason Acquisition" Brewer.
I would expect the last 2 spots to go to pitchers like Mejia, Feltman, Putnam, and Sharwyn at some point. And to get all 4, there are a few expendables like Walden and Shepherd and possibly even Sam Travis who might get DFA'd. We might even see Mejia on opening day, since Dombrowski says he believes closers need a special mentality (although his history does make me question if he believes it or to what extent he does) and Mejia is the most experienced closer in the entire Sox system.
I'd like to see the Sox ad another bullpen arm - notably Josh Fields - but I don't think it's going to happen unless a minor league deal is involved...