Complex sentence: Spotnitz, however, acknowledged that this episode was necessary to help explain the complex mythology of the show; he called the episode the "biggest chapter we had time to explore in the nine years we were on the air".
Split into simpler sentences: Spotnitz, however, acknowledged that this episode was necessary to help explain the complex mythology of the show. He called the episode the "biggest chapter we had time to explore in the nine years we were on the air".