The problem with PGs coming into the collegiate game this day and age is that they normally don't have the fundamentals to be a true PG or a good all-around PG. PGs coming out of HS would rather perfect their ability to dribble-drive, work off ISO, and shoot from outside instead of set up plays, find passing lanes, and play defense. When these unrefined players get to college, they're either the best scorer on the team or they're playing with a bunch of other talented guys, which almost mandates that they become a distributor first; a role they're not used to. And before they even begin to scratch the surface, they end up transferring or declaring.
Conversely, the guys who do possess many of the traditional PG traits, such as elite court vision, setting up plays, and being the de facto coach on the floor, are normally the unathletic kids who need more years of conditioning.
In short, it takes about 3-4 years for a good PG to develop if they're patient and receptive to coaching. There are exceptions, but not many.
This is very different from when Lute was recruiting. Those kids had the necessary coaching in high school to be more well-rounded and to understand all of the nuances of being a PG; but, also, they stayed in college for 3-4 years instead of 1-2.
You may be right in that Simmons comes in without many true PG talents, but with Trier, Alkins, Marrk, and (maybe) Ferguson in the mix, Miller will make sure that Simmons knows what his true role on the team is.