Bob Rock’s work on Mötley Crüe’s Dr. Feelgood impressed Metallica before The Black Album.
Released in 1989, Dr. Feelgood was produced by Rock and became a major hard-rock success. Metallica admired its production and believed Rock could help them realize the best record they still had in them. That interest led to his involvement with their fifth studio album.
Rock’s approach differed from the methods used on some earlier Metallica records. He asked the members to record more collaboratively, encouraged live performances in the studio, and suggested harmonic vocals for Hetfield. He also challenged the band about the lyrics and the overall presentation of the songs.
The partnership was difficult: recording involved frequent disputes, numerous takes, and repeated mixing work. Rock later described the experience as highly stressful, but he remained an important collaborator in Metallica’s next era. Flemming Rasmussen is a plausible alternative because he produced several earlier albums, not The Black Album.