Generally, it seemed the last two spots in the rotation, end of the bullpen, the bench, and center field were all up for grabs going into spring.
Chris Stratton, Ty Blach, and Derek Holland appear to be the three competing for those two rotation spots.
Stratton and Blach are my favorite candidates, as they would each make less than Holland (more room for in-season additions) and have been much better at keeping runners off the bases. Holland has also started just one game so far this spring, despite sporting a lower ERA than the young duo.