Complex sentence: At 140 pounds, he was one of the lightest quarterbacks ever to start for a major college program, and he led Michigan to back-to-back undefeated seasons and a national championship in 1923.
Split into simpler sentences: At 140 pounds, he was one of the lightest quarterbacks ever to start for a major college program. He led Michigan to back-to-back undefeated seasons and a national championship in 1923.