How Does Baritone Peter Mattei Become Wozzeck?

Mattei’s voice and stage presence have made him a popular Figaro or Don Giovanni, but the 54-year-old “was cast against type as Wozzeck, a soldier who is ground down by poverty and oppressed by sadistic authority figures before he descends into hallucinatory madness, murder and suicide.” How does he transform? – The New York Times