Complex sentence: Midoriyama since Kane Kosugi reached the final stage on SASUKE 8 and the farthest-going "American Ninja Warrior" competitor since Brent Steffensen failed on the Hang Climb in Stage 3 the previous season.
Split into simpler sentences: Midoriyama since Kane Kosugi reached the final stage on SASUKE 8. He also made it farther than any competitor in American Ninja Warrior history, surpassing Brent Steffensen, who failed on the Hang Climb in Stage 3 the previous season.