Originally Posted by AtomicDumpling
The bookmakers set the line so that they get half the bets on each side, that way they are guaranteed to make money. Once the betting starts, if more than half the bets are coming in on one side the bookmakers will adjust the line to get more bets on the other side.
When bookmakers set the line for a sporting event they are not actually trying to predict the outcome of the game, they are trying to make sure they get an equal amount of money wagered on each side of the bet. That way the losing bets will pay off the winning bets and the bookie gets to keep the 10% vigorish paid by the losers.
For this reason we can be certain that almost exactly half of the bettors will choose the over and the other half of the bettors will choose the under. If the betting ratio begins to tilt one way or the other then the bookmakers will adjust the over/under line up or down to make sure the betting rate stays at 50/50, thus ensuring themselves a 5% profit on the total amount wagered.
Yep. And that's why I wondered if the under was more likely to come in as the average bettor would look at this in a full season type of way.