He played college football for the Alabama Crimson Tide, twice earning All-American honors.

On Halloween night, against Mississippi State he would pass Johnny Musso as Alabama's all-time leading rusher.

Alabama would finish the year in the 1988 Hall of Fame Bowl, where Humphrey would score two touchdowns in a losing effort.

The Broncos, by team policy, refused to renegotiate his pay and the holdout continued late into the season.

However, by that time, newly signed Gaston Green had emerged as the team's starting running back and was on his way to completing his own 1,000-yard season.

Furthermore, Humphrey had fallen out of favor with the team's coaching and front office as a result of the holdout.

He remained on the bench as Denver made a run to the AFC Championship Game, losing to the Buffalo Bills 10–7.

The following offseason, Humphrey was traded to the Miami Dolphins in exchange for running back Sammie Smith.

With his new team, Humphrey returned to the AFC Championship Game for the second consecutive season, losing again to the Buffalo Bills.

After being out of football for two seasons, Humphrey attempted a comeback in 1995 with the Bills, but failed to make the team.

In February 1993, Humphrey was shot in his right thigh by friend and former teammate Mark Petties on an Alabama highway.

A passing motorist saw the two fighting on the highway shoulder in Alabaster, AL, and called local police.

Eight days before the shooting incident, Humphrey had been arrested for cocaine possession, aggravated assault and destruction of hotel property in Columbus, GA.[4]