Complex sentence: His title reign was largely regarded as a failure due to poor fan reaction-he was notoriously booed by the audience during several of his title defences, as the fans felt that they were inferior to those of Kobashi, his GHC Championship predecessor.
Split into simpler sentences: His title reign was largely regarded as a failure due to poor fan reaction. The fans felt that they were inferior to those of Kobashi, his GHC Championship predecessor.