Complex sentence: Jeremy attended Cathedral High School in Indianapolis where he was a classmate and teammate of fellow 2006 NFL draftee Mathias Kiwanuka, who was also Jeremy's classmate and teammate at Boston College.
Split into simpler sentences: Jeremy attended Cathedral High School in Indianapolis where he was a classmate and teammate of fellow 2006 NFL draftee Mathias Kiwanuka. Kiwanuka was also Jeremy's classmate and teammate at Boston College.