DAVE MARTIN/Associated Press

To understand Deion Sanders, you need to know about Neil O'Donnell, Larry Brown, Super Bowl XXX and the early days of free agency.

O'Donnell was the Steelers quarterback in the mid-1990s. His only qualification as a championship-caliber signal-caller was that he avoided turnovers. O'Donnell threw just seven interceptions (a very low figure for the era) during the 1995 season to get the Steelers to the Super Bowl.

Brown was a good cornerback, not a great one. He started for Cowboys Super Bowl teams in 1992 and 1993, but if anyone listed the important players from those teams, Brown would rank about 20th.

Free agency was still new, novel and a little controversial in 1995. Prime Time's signing with the Cowboys felt like crossing the Rubicon. This wasn't Reggie White revitalizing the Packers. This was a flashy attention hound (that's how Sanders was perceived by many at the time) bouncing from Atlanta to San Francisco to Dallas in search of championships, glory and the biggest possible paycheck. Sanders' joining the Cowboys was sure to destroy the concept of loyalty, imbalance the entire NFL, upset the Cowboys' precious team chemistry or anger the football gods in some other way.

Well, Prime Time added more Wow to the Wowboys without disturbing the cosmic balance. In Super Bowl XXX, he forced O'Donnell and the Steelers to reconfigure their entire game plan. O'Donnell did complete a few teeny-tiny slants in front of Sanders, but when the Steelers wanted to throw downfield, they targeted Brown. In fact, they telegraphed their passes to Brown, who earned Super Bowl MVP honors with a pair of interceptions in a game that stayed close until late in the fourth quarter.

The Steelers started over at quarterback, letting O'Donnell leave for the Jets. The Raiders, in the midst of one of their self-parody phases, signed Brown to a lucrative free-agent contract and got nothing in return.

As for that mercenary Sanders, he stuck around for five seasons during the long, slow decline of the 1990s Cowboys, earning All-Pro nods at cornerback, playing a little wide receiver and punishing the rare quarterback who dared to challenge him.

Many of the cornerbacks on this list redefined the role and expectations of the cornerback position for their era. Sanders redefined the role and expectations of the free agent and the NFL superstar as well. Prime Time put himself both on an island and in the spotlight. He unapologetically self-promoted. Sanders won championships, got paid and earned endorsements for not appearing on the highlight reel in most games. He made his teammates better and opposing quarterbacks worse, and he made sure we all knew it. He's the best there ever was at what he did, and teams have spent two decades searching in vain for a player like him.