It's a weird progression. The armies were at their most balanced state before the March Deployment if anyone remembers; Relic released information on win:loss ratios over time, and as of right before the March Deployment they were nearly dead even. Then the Deployment shook everything up, and we dealt with the balance growing pains of the new combat system. Then, once everything was close to even again (at least in perceived balance) before WFA, it's shaken up once more.That graph they showed had absolutely no dates. Also before the march deployment patch the balance was a very harsh early game vs late game balance. Even if it resulted in a 1:1 win ratio it was still a terrible way to balance.
Relic did manage to balance the teams twice before into at least an acceptable state, but it took a lot of time and they were only working with two factions. Now? I can only imagine it's going to take longer, with a harder hit to peoples' patience.
Besides it's not like we know what the current win ratio is anyway. For all we know it's still split rather even.