His power is definitely legit. His average and his defense I am far more skeptical of. Its possible that his .357 BABIP is sustainable, but if it comes down, then he is more likely a .250ish hitter with 40-50 home run power. His defense was basically average this year and it will decline steeply over the next few years. So instead of him being an 8 WAR player, I think he is more likely to be a 5 WAR player. Its possible that his defense becomes awful and he becomes a better version of Khris Davis. That still has a lot of value, but isn't really a superstar. If he can somehow manage to remain an average defender and maintain a high BABIP, he is a superstar.