If healthy Simmons will be on the race for ROY based on minutes, touches and his ability to rack up assists and rebounds, no doubt. I'd say he's about top-5 right now, but we'll have a more informed opinion during the preseason, once we see the type of offense the Sixers try to run.
Overall I'm not as big of a fan of him as others. The talent is there but I don't like his approach to the game and I think he's going to struggle with the physicality and pace of the NBA the first couple of years. The turnovers, the lack of defense and shooting and his fear of looking at the basket consistently (specially from beyond 15ft) won't help either. Maybe something's changed over the course of the year from what we saw at LSU, but he'll have to prove it in front of much tougher competition, and it may not be that easy with two bigger talents like Embiid and Fultz around.