LOL PER. Citing PER to counter to criticism involving offensive efficiency is folly. As a metric, PER is known for overvaluing high usage, inefficient players.
Cousins is great at everything in the boxscore but shooting, fouling, and turnovers. In those deficiencies, he ranges from about average to terrible.
He's a talented player, no doubt there. Perhaps some his weaknesses are exposed due to poor team composition. A solid point guard who can take some of the ball handling duties away from Cousins may help improve his prodigious turnover rate, for example.