The Metropolitan opera has announced a second cast change for its production of “Eugene Onegin.” The company said that mezzo-soprano Larissa Diadkova will sing the role of Filippyevna, replacing Stephanie Blythe, who has withdrawn. Diadkova made her company debut in 1996 singing Madelon in Giordano’s “Andrea Chénier” and has since performed Azucena in Verdi’s “Il Trovatore,” Amneris in Verdi’s “Aida,” Herodias {…}