sentences:  He played five years in the National Football League (NFL) with the Green Bay Packers, leading them to the NFL Championship in 1939.He retired after the 1942 season to become an assistant coach at his alma mater, Purdue University, and the following year became its head coach for three seasons.Isbell was the head coach of the Baltimore Colts of the All-America Football Conference from 1947 to 1949, resigning after four winless games.