During his career, Manfredy has defeated Arturo Gatti (by knockout) and more recently, Julio Diaz (by a split decision). He has also fought such notables as Floyd Mayweather Jr and Paul Spadafora. Manfredy currently sports a lifetime record of 42-8-1 (31 knockouts).
A frequent contender, Manfredy has never won a major world title, losing in each of four attempts.
Manfredy, nicknamed The Devil because of a once reckless lifestyle and of his boxing style, converted to Christianity after a career threatening motorcycle accident.
He wears a tattoo of the Puerto Rican Flag on his shoulder.