 Marrero made his major league debut when he was 38 years old, and was one of the oldest players in the league throughout the duration of his time in the major leagues.He was a popular star in his native Cuba, where he had a long and successful career in amateur baseball, pitching for Cuba in several Amateur World Series competitions, and playing several excellent seasons with the professional Cuban League and the minor league Havana Cubans.His nicknames in Cuba were "El Guajiro de Laberinto" (The Peasant from Laberinto), reflecting his rural origins, "El Premier", and "El Curvo."