He attended Banneker High School in College Park, Georgia, playing football for head coach James Fletcher, graduating class of 2001. In 2000, he was named to The Atlanta Journal-Constitution Super Southern 100, Top 50 in Georgia, Class AAA All-State first-team, and Marvelous Metro 11 squad as a defensive back during his senior year. He also received Georgia Sports Writers Association All-State and Super Prep All-Dixie Team accolades. He was named one of the top 25 safeties in the country by Student Sports Magazine. As a senior, he recorded 89 tackles, six forced fumbles, four interceptions, and 14 pass break-ups. He also had an 88-yard kickoff return for a touchdown and a 65-yard punt return for a score that year and helped his team to the 2000 Class AAA state playoffs with a 9-2 record. As a member of the basketball team, he was invited to play in the 2001 Georgia North-South All-Star Game.
While attending Georgia, he registered 176 of his 260 career tackles, eleven of his thirteen quarterback pressures and all 7.5 of his stops behind the line of scrimmage during his last two seasons. Blue was part of a graduating class that earned 44 victories, the most by any senior class in Georgia history. He was redshirted as a freshman in 2001. In 2002, he played as a reserve safety, appearing in every game. He finished with 42 tackles and a pass deflection. He was part of a defense that finished first in the SEC and fourth nationally in scoring defense (15.1 ppg), first in the SEC in red zone defense (58.8%), second in the SEC and 19th nationally in rushing defense (114.0 ypg), fourth in the SEC and 15th nationally in total defense (303.5 ypg), and allowed only 30 total second half points in the final seven games of the season.
The next year, he recorded 42 tackles with two quarterback pressures and three pass deflections. He was part of a Georgia defense that ranked second nationally in scoring defense (14.5 ppg), fourth in total defense (276.86 ypg), sixth in passing defense (174.50 ypg), 14th nationally in turnover margin (+.79), and fourth in number of scoreless quarters (25) among the Associated Press final Top Ten teams.
During his junior year, he was clocked at running a 9.10 100 yard dash time recipient of the Teka and John Adams Football Scholarship. He started all year at Rover, finishing second on the team with 80 tackles (64 solos), and also was credited with a 10-yard sack, three stops for losses of 12 yards and five quarterback pressures. He caused three fumbles and recovered another and deflected three passes. Blue was part of a team that has posted 42-10 record from 2001-04 (sixth best in the country), three straight seasons of 10 or more wins, three straight bowl victories, and three consecutive national top six finishes.
In his last year, he was an All-America first-team selection by the Walter Camp Football Foundation, the Associated Press and the American Football Coaches Association, adding second-team honors from The NFL Draft Report, as well as being named an All-Southeastern Conference first-team choice. He started all year at Rover, leading the team with a career-high 96 tackles (70 solos). He also added 4.5 stops for losses of 14 yards and had six quarterback pressures. He recovered and caused a fumble and intercepted two passes and deflected five others. Blue led a secondary that ranked seventh in the nation in pass defense (169.62 ypg) and pass efficiency defense (105.88 rating) while being named team co-captain. Blue majored in Child and Family Development and was a member of the Phi Beta Sigma Fraternity.