[2][3] Following high school, Keen attended Connors Agricultural College in Warner, at which he was a star athlete in football, basketball and track and field, running the quarter mile, hurdles, and for the relay team.

[3] He was given an award for being the school's best athlete and was the track team captain, leading them to the state junior college championship in consecutive years.

[12] Keen continued as a top player for Arkansas as a senior in 1936, and at the end of the year, a newspaper reported that "from his halfback post [he] has won more games for the Razorbacks than he can recall.

[1] Keen had initially accepted a position as a coach at an Arkansas school in 1937, but eventually changed his mind and signed with the Philadelphia Eagles of the National Football League (NFL) as an undrafted free agent.

"[15] He was the smallest in the Eagles' backfield, but was still considered one of their best blockers, with Bert Bell saying "He hits harder for his size than any man I've ever seen.

[16] The completion occurred in the fourth quarter at Wisconsin State Fair Park, and was an 86-yard touchdown pass to end Joe Carter.

[20] A triple-threat man, Keen appeared in five games for the Arrows, missing several due to injury, and scored two touchdowns,[21] while passing for three more.

[5][22][23] He helped the team compile a 4–3 record, placing second in the league, and at the end of the year was voted the most valuable player in the backfield.