I agree. While McFadden is a top 5 back when healthy he hasn't shown that he can play a full season. I think you will be much happier having a top player at two positions. Then you can target yor #2 back or #1 WR and not worry about your QB with your first pick. If you can get a guy like Calvin or Fitz you will have a very solid core to your team.
QB- Aaron Rodgers, Russel Wilson
RB- Doug Martin, Marshawn Lynch, Lamar Miller, Dujuan Harris
WR- Michael Crabtree, Hakeem Nicks, Jordy Nelson, Greg Jennings
TE- Jimmy Graham, Rob Housler