This story was originally published in 2018, and has been updated with betting results from the last three years.
NBA Christmas unders. You know what I'm talking about.
This was a popular trend of the 2010s, and hit at a wild rate once the league began playing five games each Christmas nearly 15 years ago.
Since 2005, the under has gone 43-27-1 on Christmas Day, covering by nearly seven points on average, according to our Bet Labs data.
But the under is only 8-7 the last three years, and 5-5 in the last two.
The earlier the game is played, the more the under has hit. The first three games of the day — starting between noon and 5:30 p.m. ET — have gone 31-13, though that trend is just 5-4 in the last three years.
Surely sportsbooks know about this by now, right? But what can they do — they're not going to stray far from the market consensus, or over-adjust lines just because it's Christmas.
Well, to find out, I contacted Mike Young, Sports Wagering and Integrity Analyst for CG Technology.
"We are certainly aware of this trend, and while it's tough to apply such a large, overarching trend to specific matchups, it has to be kept in mind when making these lines. However, I feel there are bigger factors at play than the fact that it happens to fall on a major holiday," Young said.
What are some of the factors, pray tell?
"You're onto something with the earlier time slots, as those games trend under, whether played on Christmas or on a random Sunday later in the season. Early afternoon tips disrupt the usual schedules and routines for players, generally resulting in lower scoring games," Young added.
Right he is! NBA games that have started between noon and 5 p.m ET have gone under at a 53.4% rate since 2005. It's not quite the same rate we've seen on Christmas, but then again, the sample size is over 1,200 games compared to just 45.
"Another thing is the competitive nature of these matchups. Not only are they on national TV and isolated broadcasts, they tend to be high-intensity games between playoff teams — except those involving the Knicks. The other games, Thunder-Rockets, Lakers-Warriors, Blazers-Jazz, and, especially, 76ers-Celtics, will be more like playoff games. Expect a slower pace, more attention to detail on defense, and, as a result, lower totals," Young said.
So when these lines are released and you think you're outsmarting the books by grabbing the lines as early as possible, remember that the sportsbooks know exactly what you're doing.
They know when you are sleeping. They know when you're awake. They know your address, banking info, date of birth and possibly social security number, too …
