jls,
It's hard to imagine that any syndicate could have such a big influence, especially in NFL, the most heavily bet sport on the planet (on a per game average basis, that is...the world cup of soccer is huge but an average soccer match gets much less than an average NFL game). After all, the betting public consists of millions of people, so hundreds of millions (if not billions) of dollars gets bet on each game. Are there really syndicates that can make a sizeable dent into that!?