Complex sentence: The band's assumed manager was Doc McGhee, who had previously worked with Sebastian Bach in his band Skid Row and managed Mötley Crüe, Bon Jovi, and KISS.
Split into simpler sentences: The band's assumed manager is star manager Doc McGhee, who had previously worked with Sebastian Bach during his run in his band Skid Row. McGhee has also managed Mötley Crüe, Bon Jovi, and KISS.