Here's a really fascinating read on the Raptors defense:
https://fivethirtyeight.com/features...s-really-good/
TL;DR version of it is that the Raptors offense is extremely aggressive (blitzing pick-and-rolls and dribble-hand-offs, double-teaming isos and post-ups, and jamming or switching on off-ball screens), but also highly variable in their aggression-level, meaning that some nights they'll switch it up and be really passive on certain actions.
As the article notes, most of the other teams with a high degree of variance are really bad defensive teams... they're doing it as a way to try to find something that works. The Raptors are the rare exception of being an elite defensive team that uses variance proactively.