Aeneas Williams bounced between safety and cornerback while playing with the Cardinals and mostly the Rams during the first part of this decade.
It wasn't his fault he could do it all.
Williams was a clutch player and big-play threat. I made him a cornerback for the sake of this exercise because it wasn't fair to penalize him for his versatility. I'll probably count him as a safety, too, when it's time to evaluate the best NFC West players of the decade at that position. He'll rank high there, too.
No other NFC West cornerback from 2000 to 2009 could match Williams' accomplishments.
While the Rams' offense earned most of the attention during the 2001 season, Williams was the one largely responsible for helping St. Louis advance to the Super Bowl. He returned two Brett Favre interceptions for touchdowns in the divisional round. He picked off Donovan McNabb late in the NFC title game, preserving a 29-24 victory.
Williams went to the Pro Bowl as a cornerback after that season.
Seattle's Marcus Trufant played more games and earned a Pro Bowl berth. He was a consistently good cornerback for several years during the decade. No one could match the impact Williams made.
Update: In retrospect, Nate Clements' name probably belongs on the list somewhere. He's been a good all-around cornerback for a few years.