Complex sentence: Sometime before "Pet Sounds" was released, the Beatles'former press agent Derek Taylor started working as a publicist for the group, gradually becoming aware of Brian's reputation as a "genius" among musician friends.
Split into simpler sentences: Sometime before "Pet Sounds" was released, the Beatles'former press agent Derek Taylor started working as a publicist for the group. He gradually becoming aware of Brian's reputation as a "genius" among musician friends.