There are going to be positions that they go young and unproven with, it is unavoidable when you start locking down stars. Other teams like the Pats have been doing it for a long time, and it's a requirement tbh if you want to sustain playoff runs.
Rams happen to be doing it with the OL, and in this case they have seen these guys line up against our own defense for much of last season's practices. So even though YOU haven't seen enough of them to know, the Rams have. Unless they're idiots. And I don't think they're idiots. I think Kromer has an excellent feel for these guys and knows exactly what he has.
If Allen ends up missing time at Center there might be probs. But outside of that I am not too worried.