Assuming Cavalli will not be on the OD roster, that leaves the following pitchers as likely to break camp:
rotation locks: Corbin, Gray, Gore, Williams
Back end of bullpen: Finnegan, Edwards, Harvey
Middle / Multi innings: Ramirez, Espino
Rule 5: Ward
Likelies: Arano, Thompson
That's 12. As for the other slot:
Abbott - can slide into the rotation
Ferrer - big jump, but if they want a lefty and move Erasmo or Espino into the rotation
NRI vet - Banda (bullpen)? Peralta (can start)? Kuhl?
Figure Rainey can be 60 day IL to create a slot. Probably Stras as well.