Do Line Moves Matter?
Do Line Moves Matter?
There are guys who are splitting their bankroll over a few different places so they can pick which line they want to play. This kinda arbitrage seems silly to me for the purposes of bankroll. Having to have significant extra money layed out that you won't ever play just to keep the option of shaving off a hook here or there. Seems a pain to manage reporting and/or even the need to quickly get a bet in etc.
But before you had the guys shopping lines, you had the guys trying to bet on a prediction of the lines moving. Still today I see guys who post about wanting to get there on Monday to bet into the lines and/or guys who are "waiting for the line to move the hook" before they place the bet.
And so, I decided to go find a data set that would tell me everything I needed to know about if Line Moves Matter. There was 2 ways I wanted to look at it... from the Open Line to the Close Line, when there is a change; does it change the outcome of bets against the spread and then for the total.
I also want to look at how good the line moves can predict the outcome of the bets. Since lines move for many reasons, I'm guessing this will be noisy, so will save for later.
For today, lets just see if it matters to wait or to rush....
A few methodology things....
- We will use data set that has ATS since 85 (35 years) and Totals since 91 (29 years) but does not have totals for games UNLV played in the early years.
- When you think about any bet there are 3 outcomes (not 2 as most people assume) and we view any change from 1 outcome to another as "Matters"... so for Totals you have the Over, Push, Under and for ATS you have Fav Cover, Push, Fav Does Not Cover.
- I am only caring about open and close... i realize there can be many various data points between and even outside these two markers; i simply am NOT an employee of a sports book with time and data sets to track every movement.... I am assuming that the Open and Close marks will cover 99% of the realities (when you see that data it is fairly clear as well)
- Option 1: Would have Won, Now We Push
- Option 2: Would have Won, Now We Lose
- Option 3: Would have Pushed, Now We Win
- Option 4: Would have Pushed, Now We Lose
- Option 5: Would have Lost, Now We Won
- Option 6: Would have Lost, Now we Push
As a summary; Options 3 and 5 are the best outcomes; Option 1 and 6 are Acceptable Non Losses while Option 2 and 4 are bad.
BUT since I'm going to look at this neutral, I'm not betting on any actual team here... I will simply look at things from the perspective of...
Outcome of Line Change A... Win to Loss/Loss to Win
Outcome of Line Change B.... Changes involving a Push.
Lets start with ATS and lets just first answer the questions around "Do Lines Move Matter?.
Yes but only 4.4% of the time and most in the Play In Games at 6.52% of the time and least in the Final 4 games only 1.43% of the time. So No not really. In 35 years only 99 games did the line move matter.
And recent trend says it is only going to matter 4-5 times in the entire tournament, so although more common in recent times, only up to around 6%.... the outlier was 2014 and that was 12%.
And what is even more interesting is that when you eliminate all the games that involve some form of a Pick and/or push; there is only 29 of the 99 games that the ATS winner flipped from open to close. So 29 of 2251 games or 1.2% of games all time. The fact there were 2 last year is impressive considering how rare these things happen!
Here are the games: How to Read: In 2019 Round 2 LSU was in a 3v6 match up with Maryland and they opened at -1.5 but the winner line movement was -1.5 so the closing line was -3; LSU was the SU Margin winner by 2 meaning the ATS Winner on the Opening Line was LSU but on the Closing Line was Maryland.
Lets look at the Totals and again answer the question "Do Lines Move Matter?.
Again the answer is yes they do but only 5.24% of the time and always less on the 2nd game of the weekend (odd? or reason?). When looking at the moving of totals, generally the total of all totals for the round at open to close is close to 0 at aggregate level. Here is a view of the entire data set in aggregate and then by year by round for the past 5 years; you can see Totals are NOT really moving that much from Open to Close.
And so looking at the recent trend by year on the number of games impacted, here is what we find:
In 2013 it didn't matter on a single game if you bet at the open total or closed total.... of late it has been 3 games slightly down from a nice 2 year trend of 5 that was preceded by a 2 year trend of 4; 2 years is NOT a trend....
And if we take out pushes, we are down to only 66 games in which the line change actually resulted in both the over and under being paid depending on when you bet the game. 66 of 2251 or 2.93%.
Here is the last 40 of those games...
So What?
- Picking the right team ATS or v Spread seems more important than getting the right line or total; get the bet in when you want.
- If the line moves a hook one way or the other, it probably won't mean much at all, you can still place your bet; stop with the "it's playable at 4.5 but not at 5".
- So wait? Why does Vegas move the lines, well that is simple; because it creates action. In my view some of this is just conditioned response type psychology. If the betting slows down, and you want more, change something to force people to make a new decision. And using the law of scarcity in persuasion, it drives the person to say "I want that line before it goes back down"; driving even more under bets. Keep moving the line up and down, you will keep getting action. In square pools like March Madness, this for sure works.
We all know that sometimes Vegas is looking to drive money on one side of a bet or another, not for the reason that people most think, it isn't about getting equal money in the pool; since they also take futures bets, Money Line bets, and other teasers and props PLUS parlays; they balance risk over all the various bets; not at the pool by pool level ADDITIONALLY they are a profit center for their bosses and therefore they want to make more than the vig rate.
To do that, they know how to move a line, drive in more bets and imbalance the pool with a greater chance to win the bet. In March Madness, I see them constantly play what i call the "Line Trend". There are certain "March Madness Myths" that are always overly bet since guys love to chase small sample and/or perception plays. Here is how they do it...
- Myth -- Duke is always an over, they are very good.
- The best example of this.... "Duke is always an over" so Vegas thinks the game will come in at 144, they write the line at 148, a ton of guys get the "over"; mostly squares; they let the pool get to about 60% over. Then they drop the number to 147 and even more squares start coming in over. They allow the pool to get squared hard to about 75% over; it comes at 144 and they happily pay the 25% of pool to win, take the vig from them and get the 50% of overs at full profit to them.
- OR the new version of this play is "Duke is always an over" so Vegas thinks the game will come in at 144, they write the line at 148 and a ton of guys get the "over" mostly squares at -110. They let the pool get to about 60% squared over and then they drop the odds from -110 to -105 over and -115 or -120 the under; We all know that guys who love drink tickets love $.50 discounts on $10 winners and so all sorts of guys chase the cheap bet. But as you all should know, the odds don't matter if you don't win. So now they get the pool at 75% squared off at 148; the game comes 144 and so now they are paying 25% of the pool with a % of winners paying 10% juice and % of the winners paying 15-20% juice AND the 50% of the pool at full impact to their bottom line.
- By the way... Duke is only 36% over in the games they win. Only 29% over in Round 1 wins. Only 25% in the past 10 years in Round 1 wins. If you think Duke will win in Round 1, play the under!
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