Closing Line Value
Closing line value compares the price you took with the market price near the start of an event. Consistently beating a mature closing market can be useful evidence that your process finds good prices.
Compare like with like
Use the exact same market and line when possible. If the line changes, compare implied probabilities or preserve both the number and price so the difference is not hidden.
Why the close is useful
By game time, many markets have absorbed more information and more money. That can make the closing price a useful benchmark, especially in liquid markets.
What it does not prove
One closing move does not establish skill, and some markets close with limited liquidity. Results need enough volume and context to be meaningful.
Keep the original receipt
Record the book, line, price and time when the bet was placed. Without the original terms, a later comparison can be misleading.