According to one informant, Frank Costello appointed Catena as his acting boss in 1956 when he went to jail. So when Genovese appointed him to be underboss Catena already had executive experience.
Never heard that before Rick, What is your source of that info? Second question, why would Costello need an acting boss in 1956? Third question, why would Vito trust a guy who had been his rivals acting Boss. Not saying Catena wasn't acting for Costello, Costello had a good relationship with main Genovese Jersey Capo Willie Moore until he was mercy killed in 52.