Complex sentence: He was nicknamed "El Negro Jefe" (The Black Chief) because of his dark skin (he was of Afro-Uruguayan ancestry) and the influence he had on the pitch, and especially after the unlikely victory over Brazil.
Split into simpler sentences: He was nicknamed "El Negro Jefe" (The Black Chief) because of his dark skin (he was of Afro-Uruguayan ancestry). The influence he had on the pitch, and especially after the unlikely victory over Brazil.