As for the discrepancy between guru's projections and weekly rankings, here's their explanation from the top of the rankings page.
"We invite you to compare these rankings versus our player projections. While you'll surely notice discrepancies between the two, we like to think of our player rankings as a "safer" view of who's worth starting and who's not. Remember, the projections are an estimation based on a three-week average as well as the matchup, while the rankings take into consideration the basic question in Fantasy Football: Who is the better guy to start?"
Actually I think FBG says something similar like they might rank player A higher than player B in a given week based on matchups, etc., but don't bench player B in favor of player A if player A is Adrian Peterson. You kind of have to weigh out the risk/reward yourself each week based on your team and opponent.
Since FBG's projections are better, their rankings are better. If you know the guru sux but your league mates don't, that's an advantage. If you're in a public league playing against random people you don't know, they are probably relying on the guru. If you're in a premium league, all your league probably mates already knew to ignore the guru.