Understanding the NBA Betting System

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A fairly old NBA betting system has made a comeback, although with an addition, essentially making it a two-part system. The reported record was over 60-percent last season, so it appears to be working as well as ever.​​

It was first called the Christmas System, as it wouldn't take effect until after Christmas, giving every team the opportunity to play roughly 25 games or more. Currently, the system is being used after each team has played approximately 20 games, which will be around Dec.

12 this season.

The First System

The first system is fairly easy to use, although it may sound a bit complicated the first time you read it. It will soon become second nature, however, so don't worry.

The first step is to take the winning percentage of each team, which is easily found online or in any newspaper, and subtract the lower winning percentage from the higher percentage.

For example, if the Celtics have a winning percentage of .750 and the Atlanta Hawks have a winning percentage of .450, the difference is .300. We will drop the decimals for ease of use with the system.

The second step is to dive the percentage differential by 20. In this case, we will divide 300 by 20 for a total of 15, which would mean our rough line on the game is Boston by 15 points.

Allow three points to the home team, so Boston would be -12 on the road or -18 if the Celtics are at home.

Subtract the point spread from the favored team and if the difference is 10 or greater, you would have a play.

So, if the Celtics were favored by 2.0 points or less, or were the underdog on the road, they would be a play, as 12 - 2 = 10. If the Celtics were at home, they could be favored by as much as 8 points to be a play, as 18 - 8 = 10.

If the Celtics were favored by three or more on the road, or nine or more at home, there would be no play, as the difference is less than 10 points.

There are several qualifiers, such as the team cannot be in the second of back-to-back games, cannot have an injured starter, and no games with a point spread of 10 or more points is considered.

One more example:
If the Pistons have a winning percentage of .800 and the Jazz have a winning percentage of .400, the difference is 400, which would make the Pistons a 20-point favorite. At home, Detroit would be favored by 23, while the Pistons would be a 17-point favorite on the road.

Detroit would be a play at home if it was favored by 9.5 points or less, and would be a play on the road if it was favored by 7.5 points or less.

Part Two

The second part of the system is a bit more complicated, as it involves taking the underdog when they go from a negative situation to a positive based on the line. The first part of the system is done in the exact same manner as the first example, in that you take the winning percentages and use the divider of 20.

For example, if the 76ers have a winning percentage of .400 and the Clippers have a winning percentage of .320, the 76ers would be rough favorites of four points.

If the 76ers are at home, Philadelphia is favored by seven (+7) and one the road the 76ers are favored by one (+1).

From the Clippers' perspective, they are seven-point underdogs on the road, which is (-7), while at home, the Clippers are one-point underdogs (-1).

When you factor in the point spread, the Clippers have the possibility of going from a negative figure to a positive figure and could possibly be a play.

If the 76ers are favored by 8 to 9.5 points at home, the Clippers would be the play, as they go from (-7) to (+1). (Remember we exclude games where the point spread is 10 points or more.)

If the 76ers are favored by 2 to 9.5 points on the road, the Clippers would again be the play, as they will go from (-1) to (+1) or greater.

Once again, the same qualifiers of back-to-back games being tossed out and staying away from teams with an injured starter.

As with all systems, just because something has worked in the past does not mean it will work in the future.

But the system is certainly something that should be tracked over the course of the season.