He played college football for the Clemson Tigers, earning consensus All-American honors in 1986.
Flagler attended Fernandina Beach High School, where as a senior he posted 1,683 rushing yards on 200 carries and 20 touchdowns, including one of the greatest games in Northeast Florida high school history, when against West Nassau (October 23, 1981) he had 405 rushing yards and 7 touchdowns.
[5] On September 26, 1990, he was signed as a free agent by the Phoenix Cardinals for depth purposes, after Ron Wolfley was lost for the year.
[6] On August 12, 1991, he was traded to the San Francisco 49ers in exchange for a conditional draft choice (not exercised).
[7] Flagler was cut on August 26, 1991, when the San Francisco 49ers chose to keep veteran Spencer Tillman.