Why Vegas Oddsmakers Want Balanced Betting
When Vegas sets a spread it can also be said that they are setting the line. A spread is essentially a point penalty applied to the favored team (or, conversely, a point boost applied to the underdog) in a matchup. The goal of a spread is to have fewer bettors bet for the favorite team, seen as most likely to win, and to have enough people say that they are not likely to win OR they are not likely to win by enough points to cover the spread.
The spread seeks to move enough bettors over the line to bet on the underdog. Ultimately, bookmakers hope that 50 percent of bettors bet on one team and 50 percent bet on the other. This is called even action or balanced betting.
Balanced betting keeps sportsbooks in business. If a matchup between Team Blue and Team Red sees 80 percent of the public betting on Team Blue to win—and Team Blue does, in fact, win—then the sportsbook has a financial liability! They must pay out a hefty amount of winnings.
Sportsbooks hire bookmakers to make sure that doesn’t happen. Bookmakers use information and statistical analysis to set the line. Bookmakers apply a spread to each game that is enough of a point penalty on the favorite team to encourage more bettors to bet on the other team.
Moving the Line: Changing the Spread
Sometimes the bookmaker will set a line that they expect to generate equal action, but they get it wrong. Either the point penalty was not high enough and most of the public still votes for the favorite team. Or, the point penalty was too severe and too many bettors lock in a bet for the underdog.
For this post, we’ll consider a game between two football teams: Team Blue and Team Red.
If you have the opening line at Team Blue -3 (you would read that as, “Team Blue is a three point favorite”) and most early bettors take that bet—that Team Blue will win by more than three points—oddsmakers will want to discourage additional people from taking that bet. Thus, their bookmakers will increase the penalty to try and discourage bets on that side.
Shifting the Line One Half Point
Typically, the penalty shifts in half point increments. If too many bettors are taking the Team Blue -3 bet, then we might see the line move to Team Blue -3.5.
Remember, that half points in football, particularly half points that move bettors off of a key figure, are significant. Half points are an extra boost of penalty or encouragement for one side or another. If you have Team Blue -3,5, the importance of that extra half point is a big deal because three points equals a field goal. What happens is that if Team Blue wins the game by a field goal? You still lose your bet because of that extra half point.
Let’s look at how this works:
Spread = Team Blue -3. To get your betting score you take Team Blue’s real game score of 21 and apply your bet (-3).
Game Score: Team Blue = 21, Team Red = 17
Betting Score: Team Blue = 17, Team Two = 17
Team Blue TIES (and your bet is a push.)
Spread = Team Blue -3.5. To get your betting score you take Team Blue’s real game score of 21 and apply your bet (-3.5).
Game Score: Team Blue = 21, Team Red = 17
Betting Score: Team Blue = 16.5, Team Red = 17
Team Blue LOSES (and you lose your bet.)
The value of half points is sport specific. In some sports, such as basketball, a team may score three points quickly and easily so half points are not critical. In football, however, scoring a field goal (three points) or a touchdown (seven points) is a feat!
When the line in our example moves from Team Blue -3 to Team Blue -3.5 the bet changes substantially. In the first bet, you are saying that Team Blue will win by more than one field goal. In the second bet, you are saying that Team Blue will win by more than two field goals or a touchdown. That small-seeming half point implies a much larger victory for Team Blue and is, therefore, a much larger bet.
Most sports have key figures: numbers or scores that are more common than others. Key figures in football are particularly significant, though, because of the way football is scored and the difficulty level in scoring. In football key figures include 3, 7, 10, and 14.
Experts disagree about basketball’s key figures, but many say they are 1, 3, 5, and 7. In baseball experts are likely to call 7 and 9 key figures.
It’s a notable event in sports when oddsmakers move the line off of a key figure. We might think of that type of action as an option of last resort. If bookmakers take a football spread from 3 to 3.5, we can interpret that oddsmakers are very uncomfortable with the current betting action and they are taking a dramatic step to balance out the betting action. Experts in the sports betting world pay close attention to the key figures and how the line moves around those figures.
More on Moving the Line
Shifting the spread (also known as moving the line) is both art and science. Bookmakers rely heavily on statistical data to set and move the line. They also may rely on insider information about the players, teams, or setting for the game in question.
Given their experiences and high betting volume, the bookmaker will typically start the line within a point or two of where they needed to be to get equal action. They will then make deliberate half point moves until they found a near equal number of bets on both sides of the line.
Watching the line move can give bettors a sense of what is going on behind the scenes. If the spread starts at Team Blue -3 and we see it move to Team Blue -3.5 and then Team Blue -4, we can assume that many bettors believe Team Blue will overcome the spread’s point penalty. As the line moves, applying more of a penalty to Team Blue, most bettors can reasonably assume oddsmakers are encouraging more action on Team Red.
Reverse Line Movement
There are times when oddsmakers do not want equal betting action. If, for example, they a sportsbook has insider information that the favored team’s star player is injured (but the injury has not been made public yet), they may try to encourage more betting on the favorite team in advance of the game. In this scenario, oddsmakers know that the favorite team is no longer likely to win without the star player, and they’re attempting to generate uneven betting in their favor. Thus, when the favored team loses, oddsmakers collect more money than usual!
In our example, reverse line move would be when the spread moves from Team Blue -3 to Team Blue -2.5. Before, Team Blue had to win by more than a field goal to win the game. Now, they just need a single field goal more to win.
Given that Team Blue was already the favorite, bettors would reasonably expect the line to apply more of a penalty to Team Blue as it moves. In this case, though, we see the penalty easing. This is reverse line movement.
There are many historical examples of Vegas sportsbooks engaging in reverse line movement, attempting to get the betting public to bet for the favored team, and then right before the game the team announces that their star player is injured and out for the game. In these cases, commentators all cry out, “Oh my gosh! Who knew?!” We smile, because Vegas knew.
There is value in identifying and correctly interpreting reverse line movement, but it can be incredibly difficult to do for beginning or intermediate bettors. For advanced bettors, there is data available that reveals public betting information (which makes identifying reverse line movement easier).
Locking in A Bet
It does not matter how the line moves after you place a bet because your bet is set in stone. Bettors place a bet on the spread at the time of their bet and that remains the spread for their bet.
If you recognize that Team Blue is an excellent team and that the spread set at Team Blue -3 is a very good bet, you can take that bet and lock it in early! If the bookmakers see too many early bettors take that bet and eventually move the line, you get to keep the bet you locked in at Team Blue -3, even if it ultimately moves to Team Blue -7.
On the other side of this token, imagine that a you took Team Red +3 and the spread subsequently moves to Team Red +7. You are, unfortunately, still stuck with Team Red +3. In this example, you would have been better off waiting because you would have gotten a much larger point boost towards your betting score at the end. When you think about adding to the score you’re hoping to add as many points as possible.
Betting is also a science and an art. You need to evaluate the current line, anticipate possible line movements, and determine when, if, and how to place a bet!