Why Pinnacle is the reference price
Sportsbooks don't all set prices the same way. Most US books are built for recreational customers: they offer promotions, limit or close accounts that win consistently, and carry wider margins. A few books do the opposite. They accept large bets from professionals, run thin margins, and use that money as information, moving their prices quickly when informed bettors disagree with them. Bettors call these "sharp" books. Pinnacle is the best-known example.
Why a sharp book's price is informative
A price that thousands of informed, well-funded bettors are allowed to bet into, at low margin, gets corrected fast. If Pinnacle hangs a rebounds line that's too low, the bettors who know it's too low bet it until the price moves. Over time this makes the sharp book's price a strong summary of what the market knows. That's why bettors and researchers use it as the reference price, and why closing prices at sharp books are the usual benchmark for closing line value.
Why recreational books differ
A recreational book's main tool for managing risk is choosing who it lets bet, not how fast it moves. It can afford to be slower to update a player prop because it limits the customers most likely to exploit it. It also often copies or shades lines from the market rather than making its own. So at any moment, a recreational book's price on a given player prop can sit away from the sharp price, sometimes because it hasn't updated yet and sometimes by design.
What OpenSlate compares
The board reads DraftKings and Pinnacle every hour during the slate. For each line both books quote at the identical number (say, a player's rebounds at 5.5 at both books), it removes the margin from each book's pair of prices (how) and compares the two fair probabilities. Lines where the books have different numbers aren't compared, because a half-point difference changes the probability and would make the comparison meaningless.
The limits
- Prop markets are thinner than game lines. Pinnacle takes less money on a role player's assists than on a point spread, so its prop prices carry less information and can move more.
- Timing matters. Both books' quotes are read at specific times. A gap can reflect one book having updated and the other not yet.
- News first. The biggest disagreements are often a late injury or rest decision that one book has priced. That's why gaps of 4.5 points and up are treated as a reason to check the news, not as an opportunity.
- Agreeing with Pinnacle isn't a guarantee. A reference price is an estimate. It can be wrong on any game, and results on small samples are mostly noise.
Why not use an average of many books?
An average of recreational books mostly measures how the recreational books copy each other. One informed price is usually a better reference than many uninformed ones, which is why the board anchors to Pinnacle and treats the other books as the prices being compared.
In short: treat the sharp price as the best single estimate available, check the news when it disagrees sharply with another book, and remember that any estimate can be wrong.
More: Removing the vig: how to turn two prices into a fair probability · Closing line value, explained · Why parlays cost more than the same bets straight · Why player prop lines move · Is DraftKings or Pinnacle sharper on NBA player props? · How do I calculate a no-vig price? · What is a +EV player prop? · Why do DraftKings and Pinnacle prop lines differ? · What is a Trap Over? · Are NBA rebound unders profitable? · How do I compare sportsbook prop odds for free? · What does closing line value tell me? · How often do prop lines move before tip-off? · What is the vig on DraftKings player props? · How do injury reports move NBA prop lines? · What is a market-maker sportsbook? · Is it better to bet the over or the under on player props? · Can you make money betting player props? · Can you bet at Pinnacle from the US? · What free tools help with player prop betting? · Does betting DraftKings when it disagrees with Pinnacle work? · What does over/under mean on a player prop? · How do sportsbooks set player prop lines? · What is a sharp bettor? · How do I convert American odds to implied probability? · What is a steam move in sports betting? · What are alternate lines on player props?
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