Complex sentence: The change is rumored to have occurred in the mid- 1900s when the boy's basketball coach Russ Rebholz, piloted the Horlick team to a winning season, at which time the team became known as Reb's Rebels.
Split into simpler sentences: The change is rumored to have occurred in the mid- 1900s when the boy's basketball coach Russ Rebholz, piloted the Horlick team to a winning season. At that point, the team became known as Reb's Rebels.