He originally attained stardom as a running back at the collegiate and professional levels , and was the first NFL player to rush for more than 2,000 yards in a season . Originally attaining a public profile in sports as a running back at the collegiate and professional levels , Simpson was the first NFL player to rush for more than 2,000 yards in a season , a mark he set during the 1973 season . While five other players have passed the 2,000 rush yard mark he stands alone as the only player to ever rush for more than 2,000 yards in a 14-game season ( the NFL changed to a 16-game season in 1978 ) .