Yeager got his start in coaching as the ninth head football coach for the Fort Hays Tigers located in Hays, Kansas and he held that position for the 1935 season. His record at Fort Hays was 8–2. This ranks him 15th at Fort Hays in total wins and first at Fort Hays in winning percentage. That year, his team was declared the Central Intercollegiate Athletic Conference co-champions.
After his success at Fort Hays, Yeager was named the 16th head coach for the Iowa State University Cyclones located in Ames, Iowa and he held that position for four seasons, from 1937 until 1940. His coaching record at Iowa state was 16–19–1. This ranks him 15th at Iowa state in total wins and 14th at Iowa state in winning percentage His best season came in 1938, when the team produced a record of 7–1–1.