Courtney Brown — Retired at 28 years old in 2006
The 2000 NFL Draft was loaded with blue chip prospects like two-time All-Americans LaVar Arrington and Peter Warrick, Heisman Trophy-winning running back Ron Dayne, and future Hall of Fame linebacker Brian Urlacher. But even with guys like that in the draft, everyone considered defensive end Courtney Brown the #1 no-brainer pick. Considered to be a prototype pass rusher, Brown had all the measurables you could ask for, but lacked the most important ability for an NFL player: availability.
After a decent rookie season, Brown suffered a season-ending injury in his second year in the NFL, and then spent the rest of his highly disappointing NFL career battling continuously nagging injuries. After a failed attempt to resurrect his career in Denver in 2005, Brown was out of the NFL by 2006.