Long was the starting quarterback for the New Mexico Lobos football team from 1969 to 1971, recording consecutive winning seasons and earning player-of-the-year honors in the Western Athletic Conference in 1971. His professional career began with the BC Lions in 1972, with whom he would play 68 games in total. In 1974 he departed to the Detroit Wheels of the up-start WFL. That year he intercepted three passes for 38 return yards, and returned 20 punts for 217 yards and 14 kickoffs for 402 yards. He returned to the CFL Lions for three years and had one of his best years in 1975, when he intercepted a team high eight passes for 88 yards. A Western All-Star in 1977, Long also led the team in punt returns in his last three years, and is still the fourth leading all-time returner, with 1946 yards on 192 punt returns, with one touchdown.
Long returned to UNM as the head football coach on December 20, 1997. His overall won-loss record through the 2008 season is 65–69, including 43–31 since 2001, the best five-year stretch for Lobo football in over forty years. He is the most successful head coach in New Mexico Football history, passing Roy Johnson during the 2005 season.
He led the Lobos to three straight post-season bowl games (2003–05) for the first time in school history and the Lobos have been bowl-eligible for seven straight seasons, another record. This streak continued into the 2007 season as the Lobos accepted a bid to the New Mexico Bowl. He garnered his first bowl win as Lobo coach by defeating the Nevada Wolf Pack in the 2007 New Mexico Bowl.
After 11 seasons, and an over-all losing record, of coaching at UNM, Long decided to resign on November 17, 2008, two days after the Lobos' regular season ended. Long cited that he was not the right person to lead the program to newer heights. He added that he had no plans of retirement, and that he wanted to continue to coach as a coordinator. In 2011, he was promoted to head coach at San Diego State after two seasons as their defensive coordinator.
Long and his wife, Debby, have two daughters, Roxanne and Hannah, who are also coaches. Roxanne is the former head women's basketball coach at Rogers State University and Hannah is the head volleyball coach at Southwestern University in Georgetown, TX.