Willie Parker has won two Super Bowl rings in Pittsburgh, but still feels as though he has to prove himself. Parker, who wasn't drafted by an NFL team, has the fourth-most rushing yards in the league over the past four years. "I feel if I was drafted, nobody would have asked me that question about the three-back system," Parker told the Post-Gazette. "Maybe I'm wrong, but that's how I feel. I feel since I'm undrafted, each and every year I have to prove myself. I'm out to prove myself again."