Complex sentence: He subsequently became a featured performer as a whistler, earning the nicknames "Whistler's Mother's Boy", "The Whistling Troubador," and "the nation's best-known whistler".
Split into simpler sentences: He subsequently became a featured performer as a whistler. He earned the nicknames "Whistler's Mother's Boy", "The Whistling Troubador," and "the nation's best-known whistler".