Th NFL is a quarterback-driven league. At the mercy of the league's best pass throwers is the cornerback. The job of the cornerback is to try and limit the damage inflicted by the opposing team's most important offensive player.
A good pair of cornerbacks will cover up a lot of sins committed by a defense. Teams that can't rely on impact players in the front seven of their defense desperately need good cornerback play to avoid being torched by the Rodgers and Brees quality QBs of the league.
Conversely, a bad corner is a QBs best friend. If a corner simply cannot stick with a given receiver, a competent veteran QB will recognize that situation and exploit it over and over again.
Click through the slideshow for five cornerbacks that opposing QBs love to target.