Joakim Noah, Roy Hibbert, and Brook Lopez are some of the best young centers in the game. And they all didn't leave after their freshman year. All of them are absolute studs on the defensive side of the ball, like Embiid, with ever improving offensive games. It's easier to begin to develop your offensive game at the college level compared to being thrown in to the fire in the NBA and developing there, especially for a player like Joel Embiid who has really only played basketball for only a few years.
Andre Drummond, Enes Kanter, Daniel Orton, DeMarcus Cousins, and Anthony Davis are all examples of centers who left after their freshman year. All are at different stages in their careers. Drummond should have stayed at UConn another year, his numbers were low and he clearly had work that needed to be done on his game, but he cashed out and his development is slowing as he is trying to earn minutes. He is still young and I believe will still pan out, but if he were patient and stayed one more year, I think he would already be in the all-star talk. Kanter and Orton definitely should have stayed because they barely played at Kentucky and now are obsolete in the NBA. Cousins is talented, but has some real maturity issues. I'm not saying a year longer at Kentucky would have fixed that, because it probably wouldn't have, but he could have been on the same team as Anthony Davis, which could have really improved his defensive game.
Davis is an all star and a front-runner for the defensive player of the year, leaving early worked out for Davis because of the skill set he had. He had been a guard his whole life then grew an astounding 8 or 10 inches in high school, propelling him to the center position. His all-around experience gave him an advantage that Embiid does not have. And if Embiid wants to be at the Anthony Davis level, he should stay at Kansas another year to polish his game.
It should be easy for Embiid to keep the numbers he had this year, if he were to stay next year. Especially if Wiggins leaves, which I think he will. Seldon and Embiid will have to fill in for the missed scoring and rebounding that Wiggins provided. Embiid, if he works hard enough at those Hakeem Olajuwon moves in the post, could average 17 ppg and grab 10 rebounds per game. That combo would be deadly for Kansas and would put him at a lock for the #1 overall pick. One thing is for sure, he definitely won't get worse after staying another year.