What a sports betting model is — and how to spot a good one
A sports betting model is a system that turns a game into a number: the probability each side wins, or the true total. Compare that number to the sportsbook's price, strip out the built-in margin, and the disagreements are where bets live. That is all a model really does — it is a disciplined way of pricing games so you stop betting on the teams you like and start betting on the prices that are wrong. Closeline is one such model, running across MLB, NBA, NHL and NFL.
The hard part is not building a model; it is knowing whether yours is any good. A model that back-tests beautifully and loses live money is worse than no model at all, because it hands you false confidence. The only test that matters is out-of-sample, forward-looking, and graded honestly: picks written down before the game and settled afterward with nothing hidden. That is the bar we hold ourselves to, and it is the first thing you should demand of any model you are asked to trust.
The rest of this page is a plain-English guide to how a betting model works and how to evaluate one, using ours as the worked example. The goal is not to convince you Closeline is magic — it is not — but to give you a framework sharp enough that you could judge any model, including this one, on its merits.
The three things every model must do
One: estimate a true probability that is better calibrated than the market, using real signal (team strength, matchups, form, situation) rather than narrative. Two: remove the vig from the market price so the comparison is apples-to-apples. Three: only act when the edge clears the fees, and size the bet to the edge rather than to excitement. Miss any of the three and the model leaks money even when it "feels" right.
How to evaluate a model before you trust it
Ask four questions. Is the record public and graded, or just screenshots? Are losses shown alongside wins? Is it measured in units and ROI, not a cherry-picked win streak? And does it report closing-line value — the metric that survives variance? If a model can answer all four, it is being honest with you. Closeline is built to answer yes to every one.