Last Saturday night, as the audience readied itself for the Atlanta Opera’s opening performance of Donizetti’s Don Pasquale for the first time in the company’s history, the ante was unexpectedly raised. Following his customary salutations and the announcement of next season’s offerings, General Artistic Director Tomer Zvulun reported on the indisposition of the evening’s Ernesto, tenor Ji-Min Park, and confidently predicted an overwhelming success for his cover, Argentinian tenor Santiago Ballerini.…