Small sample size theater time, those first fifteen games or so of the season, is the period of the basketball calendar that gives me the most conflicted feelings. Standout rookie performances are exciting! New off season traded players underperforming is interesting! All of which is counterbalanced by the overreactions to miniscule on/off splits and unsustainable shooting streaks.

It’s less fun to play sample size cop on Twitter than you might think. But, there are two areas of expected regression that almost always deserve highlighting about this time of the year, opponent free throw percentage and opponent three point percentage.

Free throw defense is not a thing. Not only is there no correlation year to year, there is very little spread between teams by the end of the year. Last year opponent’s free throw percentage had a coefficient of variation (COV) of 1.1%. As of yesterday that COV was 3.8%, over three times more spread out.

Likewise three point defense is much less of a thing than it appears at this time of the year. The spread there between teams at the end of last year was a 3.7% COV, as opposed to a 10.2% COV as of Tuesday. In both cases by far the most reasonable expectation is that the outliers will regress significantly toward the mean.

If we take that expectation and apply it to each team we can get a sense of the degree in noise in the current team performances, at least on the defensive side of the ball. The table below has the top ten regression candidates in the downward direction.





The Defensive Efficiency Adjustment is calculated as if the team's opponents had shot at an average rate on both free throws and three point attempts thus far with some mitigation then applied with a generalized expected opponent's offensive rebounds based on the extra misses.

Below are the ten teams on the other side of basketball fortune so far. The Cavs may have reason to be a bit less worried than the overall defense numbers might indicate, as they have had the worst bounces in these two noisy measures, with the Phoenix Suns right behind.

To be clear, opponent free throw percentage and opponent three point percentage are not the only measures that have noise to them at this point of the season, on offense or defense. The number of threes or free throws surrendered in themselves have some variation in them at this point that will settle out over the season, as do turn overs and rebounds, But those measures have at least some more solidity to them at this point. So simply regressing say Utah's two point defense to league average without weighing how good their rim protection has been in the last two years probably does little to help actually understand their expected trajectory.

Free throw defense and three point defense act close enough to random for us to be able to pump the brakes a little on the Orlando banner raising and at least some of the Cav's October panic.