I don't think the games are fixed per se (there's no weekly calls with the commissioner where he informs the head officials which team will win which games) but refs are human and sometimes see what they expect or want to see. Or sometimes they might make quicker calls on a player they don't particularly like or let something go for a player they do. I also believe they can be influenced by the crowd although they all swear it's not true.  Finally, add in the fact that each crew has their own interpretations on judgement calls and you end up with some awfully inconsistent officiating.

I suppose it's possible that an occasional rogue official may be trying to influence the outcome of a game but I doubt they last long if they do.

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