Alright. So here’s a note on sports bets and timing. People are often confused, because they make the same bet as a friend, but the money line or spread has changed. This is not unusual. Let’s review for a moment what I said in my post on Sports Betting Basics about how Books make money. They build in a commission to each bet they book. That’s why what I think of (and sometimes call) even money bets (like the spread) are really 11-10 bets. Let’s use the spread as an example. If the book collects $110 (for the sake of easy math) from Green Bay fans and $110 from Chicago fans, and Green Bay beats the spread, they have collected $220 in bets on that. They will then return $110 in bets to Packer fans, and $100 winnings to paker fans. They will return $210 in bets, keeping $10.
Now, let’s say that there’s a lot of die-hard Packer Backers out there. Instead of $110 from each side, the Book has collected $220 from Packer Fans, and $110 from Bears fans. They have collected $330 in total bets. In addition to returning the $220 from the Packer bets, they will be expected to pay out $200 in winnings, for a total of $420 going out. We just went from a small profit to a big loss for the casino. The idea works the same with money lines and any other bet as well. In order to make money, the casino needs to book as close as humanly possible to even money on both sides of any given bet. They can then use the majority of the losing money to pay off the winners and keep a little (in the case of 11-10 bets, 10%) for themselves.
So, what do casinos do when one side of a bet is getting more action than the other? They change the bet. They will still have to honor any bets already placed with the old terms, but if the spread looks like this on Wednesday: Green Bay -6.5 Chicago +6.5 and Green Bay is getting a lot of action, the spread could look like this by Saturday night: Green Bay -10.5 Chicago +10.5. By making it more enticing to bet on Chicago, the casino is hoping to lure in more bets on the less popular side of the spread.
When I first moved to Vegas, I was told (being a Badger fan), to never bet Wisconsin over UNLV. The spread and money line were always artificially high because the Books knew that Badger fans a) always showed up in Vegas in droves for the game, and b) would always bet their team. At first I thought this was nonsense.
After learning a bit more about how Books work and how they make their money, this now makes perfect sense.
A quick note that the actual circumstances can also change a bet. For instance, if a key player gets injured, the spread and money line will be rewritten almost automatically. Also, proposition bets on big games are popular bets. For instance, you can bet on who will win the Super Bowl before the football season actually starts. As the season progresses, the odds on these bets are constantly adjusted.
In short, there are many reasons that a spread, a money line, or an over/under can change. So if you see a bet that looks too good to be true, make it. Chances are, it is too good to be true, and won’t be there for long.