In the Brad Stevens era, the Celtics have ranked in the top 5 for three-point defense each season. This is pretty incredible because three-point defense is notoriously volatile. It’s so unpredictable that many writers chalk it up to luck. The nerds at Nylon Calculus even said:
Teams have very little control over the opponent 3-point percentage. They can affect the number of attempts, but not the percentage.
Writers and pundits have shown skepticism specifically toward the Celtics’ three-point defense as well. Kevin Pelton’s model discounted Boston’s defense because of this expected regression.