You know you’re in trouble when a grand new production of Verdi’s “Aida” only catches fire midway through the second act, after the “Triumphal March”—when Amonasro shows up.

The Metropolitan Opera opened the New Year with its first new staging of Verdi’s Aida in 37 years. Regulars had every right ... and eventually, during the Triumphal Scene, instead of a parade of ...