Most of the time, betting line shifts mean that a lot of money is coming in on one side of the action.
American football, such as the National Football League (NFL) and college football (NCAA) is unique compared to the other do-called big four sports, like the Major League Baseball (MLB), the National Basketball Association (NBA), and the National Hockey League (NHL).
Those sports may play everyday (MLB) or three-four times a week (NBA, NHL), so there is not as much time for the betting lines to move.
That is not the case with football. Teams play once a week most of the time, with an occasional Thursday game.
Once the opening lines, like the money line, point spread (a forecast of the number of points by which a stronger team is expected to defeat a weaker one), and over/under totals (the expected total amount of points of both teams combined) are set, the lines then move according to the wagers placed by bettor.
Read more: How to read bettting lines in soccer?
How betting lines move depending on wagers
Here is one example of the betting line shift in American football from the 2018 NFL season. In week four, the Cincinnati Bengals traveled to face the Atlanta Falcons, and both teams’ offenses came in hot to start the campaign.
The over/under total opened at 48 points.
Bettors all over the world poured money in on the over 48, so the line moved up to 49, then 50, then finally to 51, a line shift of three points, which is pretty large in the NFL The bettors turned out to be right on the money that day, as the two teams combined for 73 points, in a 37-36 win for the Bengals.
In fact, the over of 51 was covered in the first half, with the halftime score 28-24.
Super Bowl 53 had a major line shift right after the line opened with the Los Angeles Rams as a -1 favorite.
Within days, the line had shifted to -2.5 to the New England Patriots. New England ended up winning 13-3, covering the line.
So, what causes the line to move?
Every sports bet comes with an opening line. Say the Philadelphia Eagles are playing the New York Giants. If you were to check out this game at PointsBet, you might see a line like this on the Eagles: Philadelphia -230, -4.5 (-110).
In a nutshell, this means that the Eagles are favored in both the moneyline and the point spread. Were you to bet the Eagles in the moneyline, they just need to win the game. With the point spread, they must win by a margin greater than the spread, which in this case is set at 4.5 points. So a 20-14 Eagles victory would cover this spread, since it is a six-point margin, whereas a 17-14 Philly victory would not.
Now, suppose you wanted to bet on the Eagles, but you didn’t like those odds. Waiting can work to your benefit. The next day, you might see a line like this: Philadelphia -180, -3.5 (-110).
The line has moved and suddenly, the Eagles are a better play for bettors interested in backing them. But why does this happen?
For starters, it means there’s been some action on the Giants. And what’s vital to remember is that sports betting sites are a business. And businesses are in the business of making money.
The oddsmakers are seeking to find balance in a betting line. They want to get the betting split as close to 50-50 on the two teams as possible. It’s no different than any other business. They will respond to the laws of supply and demand.
In this case, the betting public decided that giving the Giants 4.5 points was too much and gravitated toward putting their money on New York. In order to get more wagers on Philadelphia and seek to balance the ledger, the bookmakers reduce the line on the Eagles to make them a more attractive play.
That’s not the only reason why a line will move. A key injury can impact the betting odds. For instance, were the Eagles to suddenly announce that starting quarterback Carson Wentz was out with a concussion, the line on this game would be impacted significantly because such news would certainly lead to a rush of action on the Giants.
Betting sites in the USA also track where, the sharps, the professional gamblers, are putting their wagers. This is what’s known in the industry as the smart money. They bet big and such sizable wagers tend to make a betting line move.