Cousins isn't a power forward in this league.
Especially not in the east.
Cousins could probably play the four in the right circumstances but alongside Dwight Howard isn't that situation. Cousins needs a Marc Gasol type. Someone who can play away from the paint and allow Cousins to beat up smaller PFs in the post. Dwight won't do that. He'll take up all the space in the paint and force Cousins to shoot long jump shots. Bad situation offensively.
Cousins' speed and mobility defensively would be similar to a Boozer or Z-Bo type (@ PF).