He is considered an innovator of the timbales, being the first to add a small cowbell to the setup,[1][2] and popularizing the abanico.
[3] He started his career playing güiro in Félix González's orquesta típica, and rose to prominence as the timbales player of three important charangas: Orquesta de Tata Alfonso, Arcaño y sus Maravillas and Fajardo y sus Estrellas.
He learned to play several percussion instruments by himself before joining the Septeto Cuba, based in Havana.
Díaz is generally credited with the addition of the cowbell to the modern timbales setup, an innovation that expanded the sound of the instrument.
[1] Famous timbaleros such as Amadito Valdés credit him with this invention, although others have cited Antonio Orta Ferrol "Mañengue" with introducing the cowbell in 1912.