If Randall Delgado claims the injured Patrick Corbin's spot in the rotation, that would leave nine relievers, and it appears that Bo Schultz will head to Triple-A after the Australia trip.
Addison Reed, J.J. Putz, David Hernandez, Brad Ziegler, Josh Collmenter and Oliver Perez all but certainly have spots locked up, leaving a battle between lefty Joe Thatcher and righty Will Harris for the final spot.
Harris has pitched well this spring and did a nice job for the team last season.
Thatcher, meanwhile, struggled early in spring, but has pitched better of late.
One thing working in Thatcher's favor is that he is out of Minor League options, while Harris is not. That means the D-backs could option Harris down to start the season, and he could provide insurance should any of the other relievers falter or get injured.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.