NBA Cup: How the bookies haven't adjusted for the new rules
If you are an NBA betting enthusiast, you may have wondered: "Should I adjust my betting strategy for NBA cup games? After all, the rules are slightly different!" The short answer is "Yes"! Have the bookies made any adjustments? Well yes, they have, but perhaps not as efficiently as they would like to.
In this article, I will focus on NBA totals, that is the total number of points scored in a game. Punters place bets on whether the total will go over or under a line (e.g. OVER 225.5 points). The bookmakers will calculate their lines, add their margin (aka over-round) and publish their odds. Most books typically have an over-round in the range of 1-5%.
2024 Other games | 2024 Cup (Group stages) | |
#Matches | 505 | 49 |
Percentage of matches going OVER | 51.88% | 55.10% |
The bookmakers are clever, they have a lot of resources at their disposal and they manage their models and over-rounds smartly. They have fine-tuned their lines excellently: over the course of this season, 51.88% of non-cup games have gone over their lines. The 'extra' 1.88% is likely due to sample variance. However, for NBA cup games (group stages), this percentage is 55.10% a +3.22% differential.
NBA Cup Group Stage Matches are different!
In the regular season, the only numbers that matter are the number of wins and losses. So it doesn't really matter if you lose by 1 point or by 62 points (hello Trailblazers!). However, in the group stages of the NBA Cup, point differential is the tiebreaker after head-to-head. This means that even if your team is down by 30 with 5 mins left in the game, you are more likely to keep your better players on the floor and try and narrow the deficit!
Result: the total number of points scored in the game is higher than it would have been.
Blind-betting strategy
With this knowledge, let's try and develop a simple strategy. I will bet $1 on NBA totals going 'Over' for all matches. I will use historical closing odds data 2 different APIs and stats from the official NBA website. I will use consensus odds from major US bookmakers. I will do this separately for NBA Cup games (group stages) and the rest of the games.
In the figure below, I show how this strategy would work out over the current 2024 season. The black/orange lines show how our simulated portfolio would evolve over time. The table below is a summary of key statistics of both strategies.
In this period, 550+ games have been played. If I were to bet on "Over" on all non-Cup matches (labelled as "Other"), I would lose money. I would be losing out on the over-round. If the over-round were zero, I would be breaking even (and perhaps even slightly positive). Betting blindly on this outcome is a losing strategy in the long run.
On the other hand, if I were to blindly bet on totals going "Over" for Cup games, that seems to be a winning strategy with a profit of +4.9%. While this is a small sample of matches, it is not insignificant! Note that this is the profit after taking into account the bookmaker's over-round.
This aberration is likely to be a temporary one. The NBA Cup format has only been in place for 2 seasons, and it is likely that the bookmakers will soon adjust their lines and correct their error before long. But until then, make hay!