Automatic Monkey said:
The part I don't get about sports backoffs is the lines are the same for everyone and there are only two ways to play a line.
So if you bet on the Chargers to win and I bet on the Chargers to win it's the same thing. What are they going to do, throw out everybody who bets on the Chargers to win? If they are so sure it is a losing bet for the house why do they offer it at all?
I have no experience with sports betting, so this is just speculation - but perhaps it's similar to counting in BJ: when the counter increases his bet or wongs in to a table,
everyone at the table has an advantage (disregarding poor playing decisions), not just the counter. Despite that, the house will still limit or refuse his action while allowing others to play those same hands at an advantage, simply because he increases the overall proportion of money that is being wagered with a player advantage.
Of course, unlike in blackjack, in sports betting the house is supposed to have an advantage on every player wager, assuming a perfect bookmaker. So an AP can only be identified by a long history of winning play - whereas in BJ, a counter can be and often is identified based upon a single session. And even when a sports AP is positively identified, it is difficult to know whether he has an advantage on any single wager - again unlike BJ, where an analysis of deck composition by the eye will reveal that information precisely.