The Toronto Maple Leafs once burnt a top five pick on a defensive defenseman named Luke Schenn.
Toronto Maple Leafs GM at the time, Brian Burke, set the team back by years during his rein because he continued down a path that the successful teams of the future did a 180 on basically everything he believed.
Add in a complete inability to understand the salary cap, and Brian Burke is easily the worst GM the Leafs have had since the 80s.
And his biggest blunder was wasting a top five pick on a defensive defenseman whose career high is five goals and 22 points.