Why Big Line Moves Are a Big Deal

This is why big line moves are a big deal.

Key Points

– The ability to anticipate big line moves will make you a better bettor.

– Bettors should understand what causes big line moves.

Why Big Line Moves Are a Big Deal

When you first begin betting on sports, you might not truly get everything about point spreads. You might even believe that the spread for a football game is predetermined, set at the start of the week, and never changes. 

The media often references the point spread and does so as if it remains static leading up to a game. Point spreads are, of course, far from being fixed. They respond to betting in the market and adjust to reflect that betting. 

Sometimes the adjustments are minor. Other times, bettors can observe lines moving by a number of points and sometimes very quickly. It’s these large movements that are the focus of this article. 

Why do big line moves occur? Why do sports bettors find them intriguing and how should bettors approach them? Read on to find out.


Causes of Big Line Moves – Mistakes

Before a point spread is even released, professional bettors – aka, sharps – have already decided what the line on a game should be. The philosophy of sharp bettors is a little different than the typical bettor. If the line is significantly different from what they believe it should be, those bettors will make aggressive moves as soon as the line is out. 

For example, sharps view the Miami Dolphins as a -6 favorite over the New York Jets. When the line for the game is released, sportsbooks are posting Miami as a 4.5-point favorite. Sharps will pound this number heavily.

The early betting frenzy will cause big line moves and, in this case, pretty quickly. With all of that money coming in on the Dolphins, sportsbooks will move to correct the error and adjust the line accordingly. The Dolphins may end up a 6-point favorite just as sharps had predicted. 

In NFL betting, big line moves like this usually occur before most people wake up on Monday morning. As soon as the market releases point spreads for all the NFL games, sharps are active. Most casual bettors are not. 

Consistent Money on One Side of a Bet

The ultimate goal of a sportsbook is to bring in a balanced amount of betting action on both teams. Sportsbooks are then guaranteed to make money no matter what happens in the game.

One side of the bet wins and collects the money that the other side lost. The sportsbook keeps all the juice on the losing bets. This is why sportsbooks are still in business.

Now, sometimes sportsbooks are willing to maintain unbalanced action on a game. This occurs when a sportsbook is willing to gamble on the possibility of greater financial gain. However, books generally want the action on both sides of a bet to be as close as possible. 

When there is too much action on one side of a bet, sportsbooks adjust the point spread. Oftentimes, this is the result of sharp money action. Adjusting the spread, makes the other side of the wager more attractive and entices bettors. The degree of the line move is a factor of the imbalance in the action. The greater the imbalance, the higher the potential for big line moves. 

Why Big Line Moves Are a Big Deal

Injuries & Personnel Changes

An injury to a key player, or players, can cause a line to shift significantly. The more valuable the player, the bigger the line moves. Consider an injury to an NFL starting quarterback.

Quarterback is easily the most important position in football. An NFL team’s performance usually revolves around the skills of its quarterback. Imagine your starting quarterback suffering an injury in practice on a Wednesday. Imagine that quarterback is Peyton Manning.

It doesn’t matter who the backup is. The line is going to shift dramatically in favor of Manning’s opponent. It’s the same in the NBA. When a starter or two is out, lines move accordingly. When the player out is someone like Ja Morant or Luka Doncic, the line shifts even more.

Big line moves can be caused by injuries, and they can also be caused by other personnel changes. Maybe a player gets suspended or a coach just decides to rest a player (which is common in the NBA). A player could be traded as well. All of these personnel changes force big line moves.

Check the Weather for Big Line Moves

Weather affects how lines are set. If the weather forecast changes significantly after the lines have been set, the line may need to be adjusted. 

For instance, a team that relies heavily on passing might not be as appealing as they would have been if gusting winds are in the forecast. The New England Patriots and Buffalo Bills played a game in December in the 2021 season where the wind was a factor.

The wind was so much of a factor in that game that it dropped the game total from its initial 46 to below 40 at many sportsbooks by game time. In particularly severe situations like this, sportsbooks may move the lines significantly on their own before being forced to do so by betting activity.

Reverse Line Movement

What makes big line moves interesting is when they don’t make sense. Many times, public betting action will shift a line. Let’s use the Tampa Bay Buccaneers as an example. The Bucs have a tremendous public following. The public loves QB Tom Brady and backs Tampa Bay often just for that reason alone.

If the Bucs are a 3-point favorite, let’s say public betting moves the line to Tampa Bay -6. That’s a big move. Knowing a little about line movement, we might expect sportsbooks to counter and adjust the line back towards -3. Suddenly, the line shifts to Tampa Bay -8.5. How does that happen? 

Reverse line movement happens occasionally, and big line moves like that are typically the result of sharp bettors making huge bets. The sharps have some kind of information that is telling them to wager heavily on the Bucs.

If you develop the ability to spot reverse line movement, you can get on the side of the sharps. That is usually a good thing.

Anticipate Line Movement

Sometimes, big line moves come as a surprise. As an experienced bettor, this is one of those betting mistakes to avoid

If you can anticipate a significant line change, you can find value in a wager. From the example above, you wouldn’t be surprised when the line shifted from -3 to -6 on Tampa Bay. 

What was surprising was the further shift to -8.5. You didn’t expect that and you may have missed the boat on a solid wager. Anticipating line movement will help you place your bet as soon as you can take advantage of the line and the odds.

Smart bettors become very good at predicting line movement and acting accordingly.