Free agency is one of the most important factors in constructing an NFL roster. While some teams prefer to build through the draft and others like to trade to acquire star players, identifying and signing key free agents can completely change a club's fortunes.
While not all free-agent signings live up to the hype—there have been countless examples of players earning blockbuster paydays before fizzling out of the league shortly after—some have been even better than expected.
These signings have transformed organizations within a year, turning a basement-dweller into a playoff team or even a fringe contender into a Super Bowl winner thanks to their immense contributions.