In an age more generously endowed with dramatic Italian baritones, Leo Nucci might have achieved a reputation as an elegant lyric baritone with an uncommonly attractive voice. The dearth of large-voiced singers for the major Verdi baritone characters, however, created the demand that led Nucci (and his compatriot Renato Bruson) into a heavier repertory than has been congenial. Thus, he has sung with great frequency, sought out by major conductors who value his reliability and capacity for hard work, filling the big roles with sturdy competence and moderately attractive (though...