Complex sentence: The Curse of Mike Hart is a mythological concept which purports that a losing streak of the University of Michigan to Michigan State University in multiple sports stems from comments made by Michigan Wolverines football running back Mike Hart in 2007.
Split into simpler sentences: The Curse of Mike Hart is a purported curse that is responsible for the losing streak of the University of Michigan to Michigan State University in multiple sports. It stems from comments made by Michigan Wolverines football running back Mike Hart in 2007.