Mötley Crüe's Dr. Feelgood helped convince Metallica to hire producer Bob Rock for The Black Album.
Released in 1989, Dr. Feelgood demonstrated Rock's ability to give hard rock a powerful, polished, commercially effective sound. Metallica members were impressed by that production and believed Rock could help them realize the best record they still had in them.
The choice represented a change from the band's previous production history. Earlier Metallica albums had been associated with producers such as Flemming Rasmussen, while Rock brought a different emphasis on ensemble performance, vocal harmonies, and a more controlled studio presentation.
Rock's work on The Black Album did not simply copy Mötley Crüe's sound. Instead, he helped Metallica retain its heaviness while making its arrangements clearer and more accessible. That balance became one reason the 1991 album reached listeners far beyond the band's established metal audience.