In addition, Dellacroce was in prison for tax evasion at the time of Gambino's death. That made his criminal profile higher than Castellano's--Big Paul had served a short term for armed robbery as a youngster and, except for getting busted at the Apalachin meeting in '57, had no further brushes with the law. At the time of his succession, he was a more or less legitimate businessman (wholesale meat and poultry) and was in charge of the family's "white collar" rackets. So, I'm assuming, Gambino thought Castellano would attract less law enforcement attention as Don than would Dellacroce.