We get this question a fair bit at GoBet so here is a quick rundown based on how we actually use it ourselves when betting on the NFL and NBA.
The short version
You know how sportsbooks move their lines based on where the money is coming in? Normally if 80% of bettors are backing the Chiefs on Sunday the book will adjust the line to make the Chiefs more expensive.
Reverse line movement is when the opposite happens. The public is hammering one side but the line moves toward the other side instead.
The reason is sharp money.
A sportsbook might have 500 casual bettors on the Chiefs at $20 each but one professional bettor just put $50,000 on the other team.
The book knows that the professional wins long term so they move the line to respect his money rather than the 500 small bets going the other way.
How we actually use it
We look at betting percentage data before placing our weekend bets. When we see 75% or more of the tickets on one side and the line moving the wrong direction we pay attention.
It does not mean we automatically bet the other side but it tells us the sharps disagree with the crowd and that is worth knowing before we put our money down.
We have found it works best in the NFL where casual bettors love piling onto big name teams and prime time favorites. Those are the games where sharp money tends to show up on the other side.
One thing though. Always check the injury report first. If a starting quarterback just got ruled out that will move a line against the public regardless of sharp money.
We only read it as a genuine reverse line movement signal when there is no obvious news driving the move.
