Born in Gainesville, Georgia, Humphrey completed her career as Georgia's second all-time scorer and fourth all-time rebounder. Humphrey scored her 1,000th point in just 53 games, the second fastest in school history.
Humphrey was selected in the first round of the 2008 WNBA draft (11th overall) by the Detroit Shock. Halfway through her rookie season, Humphrey was traded to the Washington Mystics for veteran Taj McWilliams-Franklin. In Washington, Humphrey could take on a more prominent role than she had in Detroit.
She finished her rookie season starting 23 of the 30 games she played in. She averaged 17 minutes, 3.1 rebounds, and 8.3 points per game. One of Humphrey's strengths is her ability to stretch the defense, making her a valuable center. In her rookie season, she ranked 13th in the league in three point field goal percentage (.382, 26–68).