Frankly, Hayes, to me, had the lowest ceiling out of the three.
I see it entirely the opposite. Kreider and Miller are close to their ceiling, IMO. They improve slightly but they aren't going to magically blow up overnight.
Hayes, on the other hand, still has the potential to be a great player. Sure, he was lazy and had a terrible sophomore year. But you are discounting his rookie year, especially the firsthalf where he was fantastic. If he can play the way he played the first half of his freshman year he's a 1C. I'm not going to give odds on the chances he pulls it off, but he certainly has the talent.
This last season he was, by almost every measure, terrible. But he still put up 36 points, so it's not like he totally fell off a cliff.