NBA Odds Insights: “Live by the 3, Die by the 3”?

Posted by Alex Murphy on July 8, 2015 in

Looking back in time into the NBA odds and other data from game 2 of the 2015 Pro Hoops Finals, the Warriors jacked up 35 shots from behind the three-point arc, but only made eight of them, perhaps a factor in their paltry 93 points that they scored in a loss. If they had made their threes at their typical rate, then they would have won the game 111-95 instead of losing in a 95-93 heartbreaker.

Were the Warriors just unlucky? Their opponents, the Cleveland Cavaliers, were not a particularly good defensive team during the regular season, either overall or against perimeter shooters, although they may be better with Iman Shumpert and Matthew Dellavedova and Tristan Thompson getting more minutes because of injuries. The Cavs forced the Warriors into some bad possessions, but the Dubs also missed on some good looks, shooting just 2-for-11 on corner threes.



But there’s also the old adage: Live by the three, die by the three. If your shooters are going to get crazy hot on some nights, isn’t it inevitable that they’ll shoot a bunch of bricks on another, rendering a team’s offense more inconsistent and making it more upset-prone?

The Warriors, for instance, averaged 110 points per game in the regular season, while their scoring range ran from 98 points (at the 10th percentile) to 126 points (at the 90th percentile), a 28-point difference. That seems like a wide range … but it’s perfectly normal. The average NBA team this season had a 27-point scoring range. The average range since 1979-80 (when the 3-point shot was introduced) is 28 points.

The Warriors weren’t the league’s most three-happy team, however. They were just seventh — behind the Houston Rockets, Cleveland Cavaliers, Los Angeles Clippers, Atlanta Hawks, Philadelphia 76ers and Portland Trail Blazers. So maybe the Dubs were pretty steady, but were those other teams inconsistent?




The Cavaliers were inconsistent: Their scoring range spanned 33 points, tied for the second-highest total in the league after Oklahoma City. But Houston, which took 39 percent of its attempts from long range (easily an NBA record), had a scoring range of just 25 points, below the NBA average. The three-happy Atlanta Hawks had a scoring range of just 24 points.
What’s going on here? Are teams that shoot a lot of threes actually more consistent than others? (Maybe they’re more resilient when facing different types of defenses or benefit from having better floor spacing?)

Actually, it’s mostly just because this data is pretty noisy. I ran a regression on all NBA teams since 1979-80 to predict their scoring range based on (i) the percentage of their field goal attempts that came from behind the arc and (ii) their per-game scoring average. Both variables have a positive and highly statistically significant relationship with a team’s scoring range. Teams that score more points have a wider scoring range, and, once you control for that, teams that shoot more threes do also.

But statistical significance is not the same thing as practical significance. In the context of an actual basketball team, this result will make very little difference.




Suppose, for instance, that a team scores 100 points per game and that 40 percent of its field-goal attempts are 3-pointers — higher, even, than this year’s record-setting Rockets. Its scoring range, according to the regression analysis, projects to be 29.7 points.

What matters a lot more, of course, is how effective a team is at scoring overall. The Oklahoma City Thunder, as I mentioned, had the most inconsistent offense in the regular season. But their 10th percentile score, 88 points, was still better than two-thirds of the league because they had a high per game scoring average.

And Golden State’s 10th percentile score, 98 points, was better than what almost a third of NBA teams scored on average per game. The Golden State Warriors will have better shooting nights than they did Sunday, but their bad nights aren’t indicative of a fundamental problem — they’re just bad nights.


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