Closing Line Value, Explained

What the closing line is

Sportsbook prices move as money and information arrive. The last price before the game starts, the closing line, reflects the most information the market will ever have. For liquid markets it is widely treated as the market's best estimate of the true probability, once the bookmaker's margin is removed (see How it works).

Worked example (illustrative, not a real game)

You paid for a 45.5% chance and the market later valued it at 50.0%. That is positive CLV: you got a better price than the close. Had the line moved the other way, the same calculation would be negative. These numbers are made up to show the arithmetic.

Why it is a better scoreboard than win rate

Win rate over a few dozen bets is mostly noise. A positive-expected-value bet loses often, and a bad-priced bet can win. CLV measures the decision (the price) rather than the outcome (the result), so it converges faster and cannot be flattered by a lucky week.

Positive expected value is a statement about price, not a prediction that a bet wins.

What CLV cannot tell you

• It does not guarantee profit. Positive CLV is evidence of price quality, not a promise of results.
• It needs a large sample before an average means anything, and it is only as good as the closing prices recorded.
• Closing lines on thin markets (some props, small leagues) are less reliable estimates of true probability.
• Sportsbooks can limit or close accounts that consistently beat the close. That is a practical consideration, outside our control.

Where we stand on our own CLV

We track CLV on the picks we publish. We are not publishing an average yet: our settlement logic was corrected recently, and the sample under the corrected logic is too small to mean anything. We will publish it once it is large enough, with the sample size next to it.