Complex sentence: Under Holmgren's leadership and play calling the Green Bay Packers were consistent winners; and, he has become known as one of the best coaches in the NFL, leading them to their twelfth league championship in Super Bowl XXXI.
Split into simpler sentences: Under Holmgren's leadership and play calling the Green Bay Packers were consistent winners. He became known as one of the best coaches in the NFL, leading the Packers to their twelfth league championship in Super Bowl XXXI.