Signing on with Deep Purple/Black Sabbath producer Martin Birch, Blue Öyster Cult made more of a guitar-heavy hard rock album in Cultosaurus Erectus after flirting with pop ever since the success of Agents of Fortune.
(They also promoted this album by going out on a co-headlining tour with Sabbath.) Gone are the female backup singers, the pop hooks, the songs based on keyboard structures, and they are replaced by lots of guitar solos and a beefed-up rhythm section.
But the band still were not generating strong enough material to compete with their concert repertoire, so they found themselves in the bind of being a strong touring act unable to translate that success into record sales.