That's true that many of their 16As played opens, my point being that being the case, Riverview aren't really going to be able to depend on players who were playing in the 16s age group to come through and bolster their 1st team or their depth, as those players are already in opens. Whereas, Scots, Joeys and Kings will have boys coming through to add to 1sts or 2nds from their 2013 16As.
The other side of this is that those 16s who played last year will benefit from a season against older boys at a higher level.
You are correct in saying that the chemistry of teams is important, and we will never know how this works until we see teams in action.
It's also correct to point out that teams can improve from one year to another, but it's just as true to say that sometimes the team which is favorite based on the previous year never live up to the hype. Which way Riverview goes, we won't know for a few months.