According to Second Spectrum tracking, the percentage of their opponents' 3-point attempts that were contested was right around the league average. So was the percentage of their opponents' 3-point attempts that were off the catch (vs. off the dribble).

Are the Celtics the favorites in the East in 2018-19?

But the Celtics allowed opponents to take only 19 percent of their 3-point attempts, the lowest rate in the league, from the corners. As a whole, the league shot 35.6 percent on above-the-break threes and 39.3 percent on corner threes last season.

Celtics opponents actually shot almost 42 percent from the corners. But reducing the number of attempts that come from the corners is to better defend the 3-point line as a whole. And the 32.5 percent their opponents shot on above-the-break threes was the league's lowest mark.

The Celtics' ability to switch screens allowed them to stay in front of ball-handlers and stay at home on shooters, but their opponents' 3-point percentage was actually lowest (31.6 percent) with Aron Baynes - one guy they didn't switch with as much - on the floor. Not coincidentally, the Celtics allowed just 97.0 points per 100 possessions with Baynes on the floor, and that was the lowest on-court DefRtg among players who averaged at least 15 minutes in 40 or more games.

With the league continuing to take more threes every year, the correlation between opponent 3-point percentage and defensive efficiency on a team-by-team level only gets stronger. And with their size, scheme and smarts, the Celtics should again be a top-five team in regard to both.

Note: The above table is based on true possession counts. Other efficiency stats here are based on possession estimates (typically higher than true possession counts).