Primer on closing line value for NFL betting

When I was a kid growing up, I used to love listening to sports talk radio. Every week, different hosts would give their favorite NFL bets, and this is where I learned about things like spread betting. I forget exactly which host it was, but I remember one week he said: “you bet the line, not the game”. As a child, that didn’t make a ton of sense to me, but as an adult, it has become one of the fundamental tenets of how I bet.

Look to gain closing line value on every wager. 

What is closing line value?

I will be focusing on NFL spread betting for the purposes of this piece, but the idea of closing line value can apply to any bet. All events are placed on sportsbooks with odds, but those odds are not static. As bets come in, the books adjust the odds based on the market (the bettors), and the “closing line,” the odds right before an event begins, is often different than they were when the event was first posted.

This creates what is known as closing line value (CLV) for bettors who took a side prior to the line moving and received better odds than what the line closed at. For example, say the Chargers open up as three-point favorites (-3) against the Broncos. As bets come in, the line shifts increasingly toward the Chargers, and by kickoff, it is all the way up to -5.5. That created 2.5 points of CLV for those who bet L.A. right when the line opened up. 

How valuable is CLV?

A couple of points here or there may not seem like a huge edge in NFL games, but CLV can make a massive improvement to your win odds when betting against the spread. Sportsbook Reviews Online has every NFL opening and closing line dating back to 2007, so I decided to take a look at the edge to be had from obtaining CLV.

In the table below lies the result of every NFL game from 2007 to 2019 based on CLV. Please note that negative numbers represent sides that obtained closing line value (e.g. -2.5 would represent our Chargers example above). The table shows how often teams covered based on both the opening line and the closing line. 

As you can see, the value of CLV can be tremendous. Without knowing any additional information about the games, sides that received at least two points of CLV covered 59.3% of the time. The break-even point in NFL sides (typically priced at -110) is 52.4%, meaning these kinds of bets have a considerable edge on the house. 

The data also tells us just how accurate NFL lines are. Though there is an edge to be gained from betting lines early, there is no discernible edge in betting those same sides after the market has been corrected. 

How can we find CLV?

Therein lies the rub. We know we want to gain CLV with our bets, but it doesn’t help us if we cannot locate the sides early on that will produce it. One easy way to pick up CLV can be by tracking the news. 

Take the Texans in 2017. The team was rolling behind rookie QB Deshaun Watson and opened up as 13-point favorites against the division-rival Colts. Mid-week, Watson tore his ACL in practice and was declared out for the rest of the year. Bettors who were able to react quickly and get a bet in on the Colts were rewarded with 7.5 points of CLV that week (and an outright win). 

Of course, these situations do not grow on trees. So how else can we locate CLV before it happens? I intend on looking into this data further to see if I can find exactly that. For now, keep in mind the value in finding CLV. Remember, you bet the line, not the game.