I agree 100%. You have to use a bunch of metrics, the eye test
etc to determine. Individual statistics are a horrible method for determining defensive strength.
A Nuggets example: all year long Mason Plumlee was thought of as our defensive center. He got more block shots, is longer than Jokic and can jump much higher. Then in the playoffs it became so painfully obvious that Plumlee couldn't be on the floor because he couldn't stop his own man from scoring. He was constantly guessing and being easily moved by Aldridge and Kanter. He was one of if not the worst performer in the playoffs in terms of defensive and net rating.
Yet during the regular season even Coach Malone (an NBA coach, who knows far more than I) would sub offense for defense and move Jokic and Plumlee out depending on who had the ball. After seeing the playoffs it seems pretty obvious to me that Jokic is indeed the superior defender (although certainly matchups always play a factor). He just doesn't necessarily look the part.