7. Kellen Winslow II — Retired at 30 years old in 2013
The son of a Hall of Fame tight end and a national champion at the University of Miami, tight end Kellen Winslow II was one of the most highly-coveted players in the 2004 NFL Draft, as he was considered to be one of the precursors to the modern “athletic tight ends” we see causing so many mismatches in the NFL today. But two games into his career with the Cleveland Browns, who took him with the 6th overall pick in said draft, he suffered a season-ending broken leg, which required two operations to fix.
The following year, he infamously suffered another season-ending injury, this time to his knee, when he had an accident while messing around with his Suzuki motorcycle in a parking lot. That same injury required another surgery in 2007 as well. Winslow finished with something of a productive career, last in the NFL until 2013, but those injuries robbed him of his full potential.