Historically, the thinking has always sort of been that because of the nature of scoring in basketball that there aren't any really important spreads. However, some bettors have felt that 4 and 5 could be considered key.

First, a little background. Key numbers are spreads (or totals) that are so likely to fall (have the final score be that exact result) that book managers do not like to move off them. In the NFL, there are several key spreads with 3 (17% of final scores) and 7 (10% of outcomes) being the major ones and 10, 4, 1, 6, 14 and 13 (4% to 7% each) being the minor ones. With these numbers, book managers prefer not to change the point spread itself to balance action, but would instead rather change the associated moneyline from standard odds. For example, if the spread was -3 (at standard odds of -110 or risking $110 to win $100) and the book had heavy action on the favorite, the line would be moved to -3 (-115) instead of -3.5.

Why are key numbers so bad? Simple, they increase the likelihood of a book getting "sided" or "middled" as a result of a line move. The easiest way to define getting "sided" or "middled" is to show a quick example of each. Remember that sportsbooks try and balance action on every game (within reason) to minimize risk and maximize profits. Suppose the spread opens with Bears -3. The book takes a ton of action on the Bears and moves to -3.5 to attract money the other way. The move works and players bet heavy on the Packers +3.5 so the wagering is equal on both teams. Now, if the Bears kick a late field goal to win by 3, all the action on the Bears -3 is pushed while the bets with the Packers +3.5 are winners. The House loses money despite the balanced action because it was sided (spread landed on opening or closing line). Imagine a worse scenario: The line opened Bears -2.5 and was bet to -3.5 where the Packers bettors finally stepped in and balanced things up. Now if the game lands Bears by 3, the bets at -2.5 are winners as are the bets with the Packers +3.5. Now the House has to pay both ways (although any action at -3 or +3 is pushed) because it was middled (spread landed between opening and closing line).

This information is provided in partnership with BoDog Sportsbook

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