Not 100% positive but I think the difference is that Castillo, not on the 40 man roster, could be signed by another team , probably for no compensation, if they will pick up his contract balance. Sandoval and Ramirez balance dues count towards luxury tax because they were protected by the 40 man inclusion and are owed their contract sums. Baseball needs NFL type contracts where a cut player only gets the current year of a non guaranteed portion of the contract.