Well, those numbers I got from the first Thalmarkin versus Melhed war, which is already quite a while ago but did strike me as too easy for the Thalmarkin (40 nobles) side. It was from before the region rebalance iirc so I'm not sure how helpful that actually is. If you've still got those data, Thalmarkin had the same regions, about 30% less population, relatively weak RCs and Melhed had everything east of the mountains, south of the river, north of Marpii and uber RCs.
I have been taking that experience into account ever since and it's pretty much the reason we decided not to just attack one realm anymore but design a way to even out the odds.
There's also Luria on Dwilight, there may be other factors but I believe it's mostly the noble amount that is winning this war for us.
The thing is, everyone has enough gold nowadays, so every extra noble you have is pretty much an extra 1000 CS to add to your army. Only if you lose do you then run into gold problems.