319784:You have to beat everyone Thugmo, not just the good players who know what decks to play... The fact that someone's bad and/or shows up with a garbage deck doesn't mean they can't get lucky or have a great matchup and crush you. Obviously it's not too often, but not preparing for it solely because it happens infrequently is like not hurricane-proofing your house in Florida =/
One of the guys I know played Jonas in Boston. His second round match was against a Warlock DOT deck. I can't think of a worse matchup for Jonas than a pure ability damaged based deck, yet I suspect the DOT deck would get crushed by most other decks in the meta. Not that anyone would prepare vs. a DOT deck, just showing how matchups work sometimes.