In addition, he served as the head coach of the Los Angeles Dons of the All-America Football Conference (AAFC) from 1946 to 1947.

Playing under the head coach, Pop Warner, he became the Stanford Cardinal football team captain in 1922 and their first All-American athlete.

DeGroot was a member of the United States rugby team that won an Olympic gold medal during the 1924 competition in Paris.

[3] A journal by DeGroot about the activities of this Olympic rugby team was published throughout 23 days during July 1924 by the newspaper, The Call.

Although they lost the NFL championship for that year by one point, 15–14, to the Cleveland Rams, the Redskins won the Eastern Division title in 1945 with DeGroot as their coach.

DeGroot received his doctorate degree in education and was recognized as one of the foremost oologists and ornithologists in the United States.