The Barons finished fifth overall in the IAHL standings in 1938–39, but defeated the Springfield Indians and Providence Reds to reach the league championship series against the Philadelphia Ramblers. They won the best-of-five championship three games to one to claim the Calder Cup. Cook coached the Barons to a second Calder Cup in 1940–41, defeating the Hershey Bears in the final. Cook remained behind the Barons' bench until the conclusion of the 1942–43 American Hockey League (AHL) season. He then turned coaching duties over to his brother Bun, but remained the team's general manager.