Devers has been around for a while now. What you have been seeing is what you're going to get. Ortiz hadn't really played much before he joined Boston.
Devers is not all of sudden going to become more than he has been. He will give you his 30HR per year with bad defense. And not so great OBP for a power hitter.
If he could take the approach he did in yesterday's game with 2 walks and apply this every game he would become like Ortiz but the problem is he is too swing happy for this.