What happened: The former Chicago instructor spent 33 total seasons working in the franchise's system from 1988 to 2020. His tenure included an 18-year run as the primary architect of the major-league rotation.

Why it matters: Cooper anchored the dugout during the team's 2005 World Series championship run. He shaped the pitching staff for nearly two decades, directing the development of notable arms including Mark Buehrle and Lucas Giolito.

What to watch: The White Sox issued a public statement extending condolences to his family, friends, and fans.