I have a degree in statistics. The numbers he is citing are pointless. They say nothing about Kanter's defensive ability, which actually doesn't require a degree in statistics to understand.
Indeed, it doesn't say much about Kanter's individual defensive ability, but it might be saying something about the team's ability to perform respectably in defense even with him on the floor thanks to defensive schemes.
This is a speculation, because I haven't researched it, but those numbers might be pointing to something else. Kanter has been playing a lot more with Dante in the last month or so, while Gobert has been playing more with Trey. It might be an indication about the importance of having a perimeter defender who doesn't get beat off the dribble automatically like Trey does. In other words, I'm not saying Kanter defends well, but he might be getting put in fewer bad situation where he's likely to make a mistake by having a PG who actually keeps up with his assignment in the pick and roll