All of that talk came from fans who have gotten spoiled seeing the likes of Miazga and Adams take MLS by storm as a teenager, when in reality that's the exception and not the rule. I don't think anyone who watched CCJ regularly for RB2 was that confident he'd step into the lineup day 1.
If Rza and Davis keep struggling and he still can't find minutes, that'd be a little disappointing. But I'm not reading into his lack of minutes yet, that's the normal case for a 19 year old, even a talented one.
The weird thing is that a lot of that talk was coming right from the team. Armas (or maybe it was Dennis) saying that he's ahead of Adams at his age and stuff like that. A lot of the people who watched RB2 were more tentative.