How are projected rankings calculated in Yahoo Fantasy Football?

There is absolutely no explanation anywhere that I can find that explains how the Yahoo projected rankings are calculated for Fantasy Football. They don't seem reliable. Here's an example: Jerious Norwood currently has a projected rank of 53 for the 2007 season. He is the second string running back to Warrick Dunn who is ranked at 91. If you look at past performance (such as 2006), Dunn is much better than Norwood. Why is the ranking so off? Can I trust this stat?