The Philadelphia Eagles had 50-1 odds to win Super Bowl LII in early August of last year, per OddsShark (h/t Gary Davenport of Bleacher Report). The Eagles were coming off an uninspiring 7-9 season, and they weren't listed among the preseason favorites to hoist the Lombardi Trophy. However, the Eagles dominated the league in 2017 en route to a Super Bowl win.
In retrospect, some signs were there in 2016. Despite the losing record, Philadelphia outscored its opponents by 36 points. The Eagles also crushed the Pittsburgh Steelers, 34-3, and beat three other playoff teams (the New York Giants, Atlanta Falcons and Dallas Cowboys).