It’s easy to forget that a significant minority of analysts thought that Leaf had more long-term upside than Peyton Manning before the 1998 NFL Draft. The Chargers secured Leaf as the second overall pick after Manning went to Indianapolis. However, these NFL quarterbacks had contrasting careers as Leaf experienced the worst of lows.
Leaf was one of the biggest busts in history because he never reached his full potential. Yes, a wrist injury damaged his prospects but there were massive problems before this. His immaturity and personal issues made him a nightmare for coaches to deal with. Leaf’s career was over before he inevitably walked away from the NFL (via Deadspin).