As I see it, Post count, Reputation and Awards cover three somewhat separate areas
Post count: Forum activity. It does not provide information on the quality or reliability on one's posts (One can have a thousand good posts in a year, or could also spam them out in a week if they are clever enough to bypass mods)
Reputation: Originality. As I can see, +rep is added when one posts something new - be that a completely new deck or card, or just an interesting spin on it - or for a really helpful comment.
(Of course post count also adds reputation, but not much, so we can forget that for now.) The problem with this is that if one has been a member for a long time, they had a lot more chances to post new ideas. There are few new ideas to be created - Decks? hardly any. Cards? Not too many, and unlikely to be ever added - so most of the time someone comes up with something, the response is 'Simpsons already did it'
Awards: Gameplay. Most of the awards I have seen were added for one PvP event or another. Other community events seem to be under represented - whether not awarded or winners inactive I cannot tell. The problem with this is that it does not reflect contribution. One could be The PvP Master, win every single match, get all the awards - and otherwise ignore the community
So, for a new member, of these three, Reputation is the best option to determine whether an answer to their question is reliable or not
(Yes, an asnwer from a Staff member is more clearly so, but most of the times it's non-staffers who get to the scene first)