"Cassel remained one of the NYCO's leading baritones up through the Fall of 1954, giving a total of 126 performances with the company.He portrayed such roles as Amelia's Husband in Gian Carlo Menotti's "Amelia Goes to the Ball", the Count in Wolfgang Amadeus Mozart's "Le nozze di Figaro", Dapertutto in "The Tales of Hoffmann", Escamillo in Bizet's "Carmen", Ford in Verdi's "Falstaff", Gerard in Umberto Giordano's "Andrea Chénier", Giorgio Germont in Verdi's "La traviata", John the Baptist in Richard Strauss's "Salome", Ramiro in Maurice Ravel's "L'heure espagnole", and the title roles in Mozart's "Don Giovanni" and Verdi's "Rigoletto" among others.