Maybe a mod will sticky this site so this never ending dog chasing its' tail issue will meet a merciful,quick end...
As you all know, when you place a straight wager on the pointspread of a football or basketball game, you need to risk $110 to win $100. The $10 difference between risk and payout is known as the juice, or the vigorish, or “vig” and is the reason sportsbooks are in business. Sportsbooks essentially act as a broker between you and another player who wants to bet on the other team and collects the small commission as compensation for brokering the deal and handling the transfer of funds between the two of you. This is important to understand, because it leads me to the biggest misconception in sports wagering. The pointspread is not the handicapper’s predicted margin-of-victory, but it is in fact the handicapper’s prediction of what number will be required to split the wagering evenly on both teams. Understanding that little tid-bit is the first step towards taking advantage of the numbers
Pointspreads Explained: How bookmakers set the betting line | TheSpread.com
the point spread has ZERO to do with how YOU feel one team is better than the other. You and all your friends and even all the people you don't like can scream and shout that the Ravens or the Pats should be giving or getting no more than three points and it STILL MEANS ZERO as far as setting the line. Get it???????
I don't imagine that the sportsbooks felt any more comfortable about setting this week's line lower after the Pats ended up covering close to double digits anyway vs HOU last Sunday, so that may also be a reason why some people feel the number is a bit higher. I haven't seen the pointspread records for popular, high scoring teams like the Pats/Broncos/Packers etc this year (currently) but I do know that Vegas was having a hell of a time with the over/under total number on Pats games, both this year and last. They couldn't move that number high enough to attract equal action on the "under," particularly in divisional matchups where we tend to go over a lot in the past few years.
It all comes down to your explanation. They try to bring as much equal action as possible on both sides, so that they can sit back, relax, and collect their 10% on each bet. Sometimes that does not happen, but that is obviously the intended outcome. They also make up for some of it by driving the "vig" or the juice up before the number changes. It's certainly not always just 10 percent.
For example, if you wanted to bet NE-8 right now you could at -115 (it's actually 15 percent in a lot of places), but the more action they see on this price will drive the "vig" up even more BEFORE the line actually moves on the point scale. As more and more people continue to hammer the -8 line, the "vig" will move up too. I have had plenty of examples where I've had to wager -120 or even -125 to win back 100 (equaling 20 or 25 percent juice) on a bet if they aren't ready to move the number yet. I would imagine that also helps to offset any one sided games even more.
Once the juice becomes too high to attract equal betting (usually around -120 or -125) only THEN do they move the actual number.
Keep in mind that these playoff games also draw a ton of proposition bets. Over/Under on number of passing yards from Tom Brady, Joe Flacco. The same with rushing yards for different players, etc. Those prop bets often are one sided, and based a lot more on the "vig" moving up/down, rather than the number of yards moving up/down. There are many bets that don't pay nearly enough (just like in baseball, which is not based on a pointspread system for about 90% of their action, although that option does exist) to prove worthy enough to waste your time or money on, just due to the fact that Vegas has the juice set at -150 and -160 on many items.