So I think I know what is happening with GW matching.
First, you need to work out your personal GW metric. This is the mid power point between your top 5 toons and highest arena team power.
The GW nodes are a % of this score. The ones that have change significantly since last update are:
Node 6 - 95%
Node 9 - 100%
Node 11 - 105%
Node 12 - 115%
So why are the top players getting easy nodes 12 (and occasionally 11)? I think it is because the max power possible is 42,411. Therefore, if your GW metric plus 5% or 15% is greater than this score, the match-making logarithm can't provide you with a suitable match and is instead providing a ridiculously easy team (not sure whether this is intentional)
