[2] He played college football for the Texas Longhorns from 1962 to 1964 and was selected by the Giants in the 11th round of the 1965 NFL draft.

He was a member of the 1963 Texas Longhorns football team, which won a national championship, although he missed most of the season to injury and illness.

During his six years in the NFL, Koy played in 79 games, carried 414 times and gained 1,723 yards.

Koy was also the Giants' punter with a 38.5 yard average, and returned 30 kicks during his career.

He later worked for Austin County State Bank, which was eventually sold to Wells Fargo.