Two things are for sure: Cousins is a better passer than Golden State has had at the center position since they traded Bogut. He's going to open up their playbook in a way that they haven't been able to do since 2016.
The second thing is that he is also lowkey their best low-post defender they've had since Bogut. He's not as effective defending from the weak side or in the pick and roll as either McGee or Looney, but if he can just manage to not be a liability defending PNR, he's going to make them tough to deal with inside.