If you've watched this Celtics-Raptors second-round series, you've probably noticed Toronto relies pretty heavily on a zone defense.
What you may not have noticed is that the Raptors' unique defense is consistently exploiting a blind spot of NBA officiating: the defensive three-second violation.
As NBC Sports' Tom Haberstroh laid out in his latest column, defensive three seconds is one of the most overlooked calls in the NBA -- especially at the end of games.
According to The Pudding's examination of the league's Last Two Minute reports, there were 141 defensive three-second violations in the last two minutes of close games between 2015 and 2018, and only one was called.
That stat may explain why Raptors star Kyle Lowry was able to stay in the paint for a good five seconds on Boston's final possession of Game 3 to stop Kemba Walker's drive and force him to make an incredible pass to Daniel Theis for a go-ahead dunk with five seconds to play.
Lowry's camp-out was no anomaly for Toronto, which has gone to zone coverage 85 times this postseason -- more than the next two closest teams combined, per Haberstroh.
Zone defenses usually increase the likelihood of defensive three seconds with big men glued to the restricted area. But the Raptors have yet to be called for that violation this entire postseason, essentially getting free reign to push the envelope on legal defenses.
Toronto's defensive efforts haven't been enough to prevent the C's from taking a 3-2 series lead with a chance to advance to the Eastern Conference Finals with a win in Wednesday's Game 6.
But the Raptors' zone has slowed the Celtics more than their man coverage, so if it weren't for their exploitation of this loophole, this series might already be over.