What Causes Big Line Moves?

Big line moves are very intriguing to me. They happen every day, and when they do, it’s another chance to learn something about handicapping to try and determine exactly why they moved. The more you can do this, the better off you will be when it comes to beating the books through sports betting on a consistent basis.

Many games only move a point or two, but some will move 5-6 points, and that’s when you know something is going on. The general public believes these games are fixed, but that’s far from the case. The fact of the matter is that oddsmakers simply make mistakes sometimes, or they set a tempting line hoping the public will pour in on one side, which are the sharpest oddsmakers out there.

Lines react to the bets that are made, and then they are adjusted accordingly. It’s the big line moves that I want to focus on in this article. Let’s take a look at some of the causes of big line moves, which ones are really important to follow, and then a solution to beating these big moves.


Early Money Jumping On a Mistake – The sharpest of handicappers and professional bettors will have already established a line for each game before the books even release them. If the line differs significantly from their number, they will get as many bets down as possible on their preferred side. If there are several bettors who disagree with the line, then the action will be heavy early on. The oddsmakers will then have to adjust the line accordingly. The general public won’t even have time to get in themselves before the move because it will be too late by the time they wake up Monday morning.

Steady One-Sided Action – The goal of most sportsbooks is to get even action on both sides. If the same amount of money is bet on both sides, they are guaranteed to make a profit from the juice. The sharp oddsmakers will be willing to take a gamble sometimes and let most the action ride on one side. But, if they aren’t confident with the line they set originally and all the action is coming in on one side, they will certainly move the line a couple points to try and balance it out, and sometimes more. But they do not want to get middled, so sometimes they will take a stand and let the action come in. You know they’re not very confident in the original line if you see a big move.

Injuries or Changes at Key Positions – Books don’t normally release lines until they have all of the injury information they need. However, there are still times where an unforeseen injury happens to a key player that they couldn’t have anticipated. If the star quarterback gets injured in practice and will be forced out of action, there’s a good chance the line is going to move significantly. Also, suspensions, trades and other major personnel changes could be responsible for the moves.

Weather – A weather forecast can change a game dramatically. This obviously doesn’t matter at all in basketball, and but it has an impact on a game in both baseball and football. Baseball totals will move in a big way depending on whether or not the wind is blowing in or out. Football totals will be lowered by multiple points if it’s an outdoor game and heavy rain or snow is expected. Also, heavy rain and snow almost always benefits the team with a better rushing attack, so that could alter the point spread a few points as well. Heavy wind will negatively affect passing teams.

Important Moves to Follow

Move Goes in the Opposite Direction of the Action – This is what we call a reverse line move. When 70% or more of the bets have been placed on one side, yet the line is moving the other way. This happens a lot when public teams are playing because most the action is always going to be on them. The oddsmakers will get tipped off that several sharp bettors that they respect have put big money on the other side. They are much more worried about more sharp action coming in on the other team than they are about letting the bets pour in on the public team. It takes several big bets to cause a reverse line move, so you know that the sharp action is on that side. You almost never want to get caught betting against a reverse line move.

Move Goes Through a Key Number – This is very important in football. Books almost never move a line through a key number, especially 3. They don’t want to get middled because so many football games, especially the NFL, end with a 3-point margin. So, if they are moving a line from -2.5 to -3.5, or +3.5 to +2.5, you almost always want to follow the line move. There must be a very strong reason for a move through a key number, and it’s usually because they set a poor original line. Oddsmakers are essentially telling you that not moving it would put them at a bigger risk of a loss than a middle would.

An Extremely Big Move – Lines move one or two points all the time. But, it’s rare that you see a line move as much as 5-6 points, and sometimes more. These moves usually only happen in college sports, especially college football. When it does move 5 points or more, you know something really bizarre has gone on, and you need to try and figure out what it is.

How to Beat Big Line Moves

As stated before, I love learning from big line moves because it makes me a better handicapper going forward. In some cases the line moves come as a surprise and we couldn’t have predicted it, but in most cases you can pinpoint a reason and learn how to use that to your advantage. It’s not surprising when a big line moves happens when a public team is playing an unpopular one. When you can see that coming, your best bet is to figure out which side you want to back early. By doing so, you can get a better line on the public team early, or you can wait it out and get a better line on the unpopular team later on in the week. That’s why it is very important that you do your handicapping by the time that the lines are released so that you have a better chance of beating these big moves.

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