I think the reason why Barbollini uses Gioli as OPP is Gioli isn't that fast at blocking at the net.Barbollini wants to use her fast attacks with using her as OPP and chooses better blocking players like Arrighetti and Anzanello. And I think there is not a huge differences between Ortolani(If we concider her play so far) and Gİoli(OPP).
anzanello has a good block?maybe in the league,but not the national team.she is so heavy and slow so missed many chances to block!the best MB are arrighetti-gioli.anzanello even can't be the third MB than guiggi.