In August 1992, Díaz beat the former IBF Champion Julio César Borboa.
[1] On October 19, 1996, Joel lost a twelve-round decision to undefeated IBF lightweight champion Philip Holiday in Wembley Indoor Arena, Johannesburg.
This win made Díaz the number one rated contender and mandatory to then WBC lightweight champion, Stevie Johnston.
Due to a detached retina that left him blind from one eye Díaz retired from boxing.
Some of the notable fighters who have trained under Díaz include, Antonio Díaz, Julio Díaz, Timothy Bradley, Abner Mares, Vicente Escobedo, Israil Madrimov, Shakhram Giyasov, Murodjon Akhmadaliev, Bektemir Melikuziev, Otabek Kholmatov, UFC fighter Cub Swanson and Ruslan Provodnikov.