When placing a bet, the odds are not random by any stretch. The sportsbooks have a ton of algorithms for each type of bet, and they run simulations to predict how games will go as well. With that being said, when they release the lines for games, they are not set in stone for a multitude of reasons. All of these reasons are the sportsbooks trying to get the upper hand on the public, as well as trying to limit their potential losses on a single line. Once the spread is set, the line usually changes first before the spread itself changes, as they try to see the trends that people are going to be playing.
Change in Player Status
The first reason that lines move is due to changes in the players participating in the match. Across all sports, injuries happen, but the outcome of each game is impacted by the players participating in it more than anything. Let’s say that the Dallas Mavericks are playing the Celtics and are at full strength at first glance and are -7. If they all of a sudden announce that Luka Doncic is not playing, it would be wise to fade the Mavericks and take the Celtics +7, as the -7 factored in the superstar player of the Mavericks. What the sportsbooks then do is lock the line to make sure no one can bet on the game and run their calculations again on the fly. If this is the only factor to change, they will most likely come back with the line at -4.5 or lower for the Mavericks.
Money Moving the Lines
The other reason that lines move is if a game is taking a lot of action. Let’s use the Bengals @ Chiefs game as an example. The line opened on Monday, January 24th at Chiefs -7 and -110. It stayed the same until Thursday night when it moved in favor of the Chiefs to -7.5 and -110. From the opening line to just before the game, the line has changed a whopping 28 times, ranging from Chiefs -7 and -105 to -8 and -110 within this period. The NFL Playoffs are some of the most bet on games that there are, so the books trying to stay ahead and not have all of the same bets taken is understandable to try and keep the edge.
How to Approach Line Movement
Some people look to these line movements to completely determine which side that they play, while others think that they should avoid the side that is getting a lot of action and money wagered. Personally, I do not think that the lines dictate the outcomes, but sometimes people with insider information bet on games and shift the line on their own, and these bets are usually placed right before the game by “sharps.” Sharps are experienced bettors who wait until the last second to place their bets and when there is a lot of late money wagered, those games end up close more often than not from my experience.
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