Even though we may have a notion on how Climate works, we can't predict exactly what will be the state of the Arctic after the melting / refreeze seasons for instance.
Across the whole summer average temperatures have been relatively cool and, despite of this, we have seen drops in extension that didn't seem to go in hand with the temperatures we were collecting. It hasn't been until the end of August when we have started to see things decreases flatten.
I think we shouldn't break our heads, the melting season is over (or very close to) and now we have the Big picture of all of it, and its summary would be: relatively cool temperatures, extension area low, following the declining trend (not only in extension, but also on multiyear ice, slushy, etc) but obviously there is a correlation between temperatures and ice, so that's maybe why some expected lower extension numbers, but this does contradict the trend at all in my opinion. We obviously should try to keep learning from the Cryosphere, and to find out the intrincancies of the Climate, like for example why extension numbers kept falling fast until almost the end of the season despite having almost a whole summer without large positive temperature anomalies?