It probably just balances out with the large amount of games played. I'm not currently too knowledgable about the start of DC, but before it, I was in touch with most of the imbalances in the other patches; and I can tell you it was imba before. For example, in 1.3, defilers were stupidly powerful and Orc's lank of AV against them made it even worse.
From looking around I guess Necrons are the best race, though again I don't really know that much specifically. And yes, there's always bound to be some imbalances in any RTS, but in past versions of DoW the imba has been sometiming principally recognised.