Reverse line movement
Reverse line movement is when most of the bets are on one side and the line moves toward the other. It looks backward, and it isn't. A book counts dollars and knows whose dollars they are, so a line that moves against the crowd is telling you the bigger money, or the sharper money, is on the side the crowd isn't.
Why the line goes the wrong way
The public's idea of a bookie is a man who moves the line to balance the tickets. Nobody runs a book that way. A ticket for $50 and a ticket for $5,000 count the same in a percentage of bets and are nothing alike to the book.
I'll show you how it looks from behind the counter. A favorite opens at -3. Three hundred players bet it, at about $50 each, which is $15,000. A hundred players bet the underdog: ninety-six of them at $50, and four at $5,000. That is $24,800 on the dog.
| Side | Share of tickets | Share of money |
|---|---|---|
| Favorite -3 | 75.0% | 37.7% |
| Underdog +3 | 25.0% | 62.3% |
Three bets in four are on the favorite, and the book has more than six dollars in ten on the underdog. It moves the line to -2.5, to make the favorite more attractive and the dog less. Anyone reading the ticket count sees a line moving against 75 percent of the bettors and calls it reverse line movement.
There is a second reason, and it matters more. The book knows its players. If those four big bets came from accounts that have beaten the closing number for years, the line would move even if the money were level, because the book respects what those players know more than what the crowd likes. The odds movement page covers how a book decides which bets move a number.
Where the percentages come from
To see reverse line movement you need the betting percentages, and that is the weak point. The figures you see online come from books or services that publish their own counts, or estimate them. One book's 75 percent can be another's 60, and no book publishes who its sharp accounts are. A percentage of tickets, with no dollar figure beside it, tells you less than it seems to.
So I'd treat a published split as a rough sketch of where the public is. It is good at telling you which side is popular. It is poor at telling you why a line moved, and that is the part you'd need to know to bet on it.
Should you follow it
The idea behind following reverse line movement is sound: back the side the sharp money is on. The trouble is timing. By the time you see that the line went from -3 to -2.5, the price that made the underdog a good bet is gone. The players who moved it got +3. You'd be getting +2.5, and in football that half point off a 3 is one of the most expensive on the board. I wouldn't pay it for a move I only read about afterward.
There is one case where it is worth something. Books don't all move at once. When a line moves at the books that take sharp action first, the slower books can still be dealing the old number for a few minutes, and that number is the one worth having. Following a move is a matter of being early, and a bettor who checks the percentages at lunchtime is not early.
The better test of your own betting is the one the line move is pointing at. Compare the number you got with the number the game closed at, every time. A bettor who keeps beating the closing line is on the side the market moves to, whether he reads the percentages or not.
Reading a move
When a line moves, I'd ask three things before letting it change my mind. Was it the price or the number, -110 to -120 or -3 to -2.5? Did it cross a key number, which a book does only when it has to? And was there news, an injury or a change of quarterback, that explains it without any sharp money at all? Why do odds move? goes through the causes.
If none of those explain it and the crowd is on the other side, you have reverse line movement, and a reason to look again at a game. It is not a reason to bet, and it is never a reason to bet bigger than your bankroll allows. A line move is somebody else's opinion, and you've arrived after they were paid for it.