Are There Key Numbers in the NBA?

I can hardly believe February is coming to an end already. Has it really been a month since the Super Bowl already? Well, that can only mean March Madness is just around the corner so it must be time to turn our attention to basketball. Readers and clients frequently ask me if there are any key numbers in basketball. 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 so I decided to follow up and see if there really are any key numbers in the NBA.

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 (4-7% each) being the minor ones. With these numbers, book managers prefer not to change the pointspread 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).

Traditional thinking on basketball has been that there are no spreads with likely enough outcomes to warrant the same type of line move. If you get action at -3, you move to -3.5. More action at -3.5, you move to -4. You get the idea. However, the data for the 2001-2002 NBA season paints a different picture since there a handful of numbers that fall enough of the time to be considered in the same category as minor key numbers in the NFL.

Late last summer I analyzed the numbers for the 2001-2002 NBA regular season in preparation for a column for a gaming magazine on basketball. Here is a summary of the most landed on scores for the season and their frequency:

  • 7-points 7.4%
  • 5-points 7.1%
  • 6-points 6.9%
  • 3-points 6.6%
  • 9-points 6.4%
  • 2-points 6.2%
  • 8-points 5.3%
  • 4-points 5.2%

These eight outcomes were the margin of victory in over half of all NBA games last year! The average margin of victory was a surprising 10.8 (boosted by a 53-point win by the T-Wolves over the Bulls in November). This does not take into account favorites or underdogs, so the likelihood of a spread of -7 actually landing is less than 7.4% because the underdog would have won by 7 in some of these cases. 1-point was the difference just 3.8% of the time so if you get to see a real buzzer beater, enjoy, as they are much rarer than most people appreciate. Ten through 14 also saw their share of games, all coming in 3.1-4.6% of the time. The drop-off is pretty severe after that.

Over the last couple of weeks, I have gathered and analyzed the numbers for this season and the results look very similar.

  • 7-points 7.3%
  • 5-points 7.3%
  • 2-points 6.5%
  • 6-points 6.4%
  • 3-points 5.8%
  • 8-points 5.6%
  • 9-points 5.1%
  • 4-points 4.3%

So far this season, these eight outcomes account for the final margin of victory in 48.4% of all NBA games (down slightly from 51.1%). Ten and 11 both have climbed slightly and are now 5.0 and 4.4% respectively. One-point wins are happening 3.6% of the time. Again, above 14 the drop-off is dramatic.

Right now I know you are asking So what? Let me try and explain how this can help you. First, you know to be very diligent in shopping for the best line if the spread is -2 to -11. This should be the case with any spread but is particularly important in this range. Getting -6.5 instead of -7 in the NBA is statistically more important than getting -3.5 instead of -4 in the NFL but very, very few bettors are aware of that fact.

Secondly, if you are going to play teasers, you now know which are the best lines to tease. Teasing a favorite down from -7.5 to -2.5 will cross 4 of the most likely outcomes of 7, 5, 6 and 3 so, such a line would have to be a much better candidate for a teaser than would be a spread of -18 or -2.

Finally, when buying points, you now can judge how valuable a half point really is. Don’t worry so much about buying to -1. A final score of 1 only lands in 3.6-3.8% of games, yet I see a lot of players buying the spread all the way to -1 (and even -.5!) Buying from -3 to -2 is a lot more valuable than is buying from -2 to -1.

Also note that many bookmakers are picking up on this trend. Ten years ago, you would never have seen an NBA line of -6 -115, but in today’s competitive environment, these lines are showing up more and more.

One quick sidebar before I sign off for this week. I recently became a father and I must say it as awe-inspiring an event as people say it is. My athletic career never amounted to much (as my coach used to say, Gillespie, you aren’t very big, but you make up for it by being slow and that isn’t a typo!enough said). However, after I finished packing some things into the car, I was walking back into the hospital to pick up my son and experienced such a feeling of euphoria and accomplishment that I now think I know how Tiger Woods felt walking the 18th fairway at Augusta knowing the Green Jacket was his. For my friends that are sports fans but not parents this is the best description I can give you.

Anyways, I hope this information helps make you a better basketball bettor. Good luck the rest of the season.

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Rob Gillespie is President of Bodog Sportsbook & Casino