Kanter's defensive rating is 100.8, which is, by the way, 8.2 points lower than Robert Williams defensive rating. The team also allows exactly 105 points per 48 minutes whether Kanter is on the court or off(Kanter's on/off court offensive #s are 117/110.

Also, Kanter's top 2 five man groupings by minutes played:
Walker, Smart, Brown, Tatum, Kanter and
Wanamaker, Edwards, Tatum, Ojeleye, Kanter
have excellent defensive numbers. That's also true for the 4th, 5th and 6th most often used Kanter groupings.
What I think this tells us is that:
1. Stevens has already figured out who to put with Kanter when he is on the floor and when in the game to use him, specifically, when he can play with 4 starters or when he is part of a unit playing the other team's bench.
2. This use of Kanter is working and his defesive limitations aren't killing the team.
3. Kanter is probably playing way better overall team defense than some are giving him credit for.
https://stats.nba.com/team/1610612738/players-traditional/?Season=2019-20&SeasonType=Regular%20Season&sort=PTS&dir=1http://www.82games.com/1920/19BOS16.HTM