In the salary-cap era, no NFL team can head into a season with above-average starters at every position. Some teams have come close -- and others have been able to mask their issues with dominant players at other positions -- but every team's weakness gets exposed.
The New England Patriots, who have won six Super Bowls and lost three more over the past two decades, provide two great examples of how weaknesses on both sides of the ball did them in during that span. The 2007 Patriots went 16-0, but when the Giants lined up excellent pass-rushers against New England's interior linemen (and Randy Moss wasn't healthy), the offense shut down.