Greer lettered for the Vols from 2000-03. Played in 49 games and had 147 tackles, three and a half sacks, eight TFLs, 33 PBUs and two interceptions. During his college career, Greer also participated in track & field. He broke the 110 m hurdles school record. Greer was a three-year starter at cornerback and broke a school record by playing in 51 games. Greer graduated from Tennessee in 2004 with a degree in psychology.
Greer was undrafted, but played for the Buffalo Bills from 2004-08 and the New Orleans Saints from 2009-13. He was a key member of the Saints team that won Super Bowl XLIV.