Why do Williams, Edwards flip-flop at the top?

Why do you have USC wide receiver Mike Williams atop your Big Board, yet have the Bears taking Michigan wideout Braylon Edwards ahead of him in your mock draft?

Dave Turrubiartes, Chicago

It's important to remember that the Big Board and my mock drafts are independent of one another and have no effect on each other. The Big Board is my personal rankings of the players I believe to be the top 25 prospects on the draft board, but that does not mean they will be the first 25 players taken. I base my first-round projection on identified team needs and what I hear from people around the league, and the opinions are not always the same as mine.

I feel Mike Williams ranks ahead of Edwards as an overall prospect because of his size but not everyone sees it that way, hence my projection that the Chicago Bears will take Edwards ahead of Williams. That could change in the coming days and weeks, though, as teams become more sure of their strategy. I have two or three possible names penciled in next to each team and changing one affects others, but shuffling the first-round projection will not necessarily affect the Big Board.