The closing line is a market's last price before the game starts. By then the market has taken in the most information and the most money, so the closing line is the best public estimate of each outcome's chance. Closing line value is how much better your price was than that.
Measuring it
Compare your price with the closing price on the same side, in implied probability:
- You bet a side at +150 (40.00%). It closes at +130 (43.48%). The market moved toward your side: you got about 3.5 points of CLV.
- You bet a side at −110 (52.38%). It closes at +100 (50.00%). The market moved away: about −2.4 points of CLV.
For spreads and totals, a move in the line counts as well as a move in the price. Taking −2.5 on a favorite that closes −3.5 is CLV, and a half point through a key number is worth more than one elsewhere (see the NFL key numbers guide).
The fairest comparison is against the closing no-vig chance, so the vig on each side does not blur the result.
Why it matters
Results take hundreds of bets to separate skill from luck. CLV shows up much sooner. A bettor who regularly beats the closing line is usually finding real value, whatever the last few results say. One who regularly gets worse than the close is usually betting into prices that are already right.
CLV is evidence, not proof. One bet's CLV says little; a long record of it says a lot.
Getting it
- Bet early when you have a view the market has not priced in yet, such as an injury or weather change you have seen first.
- Shop for the best price: the same bet at a better price is CLV before the line moves at all.
- Do not chase a move that has already happened. Betting a side after it has moved toward you is betting at the worse price.
In Unitley
get_line_movement shows how FanDuel's price and line in a market have moved: first and current price, the longest and shortest price seen, and how many times it moved. get_game_odds shows FanDuel's current price and the best price at that line across the books Unitley tracks.
Names set like this are Unitley’s tools: what your AI agent, or the analyst in the web app, calls to get these numbers. See the docs