The game is so substantially different across all modes and for different skill levels that it's never going to be balanced enough for everyone.
Brits are borderline OP in 2v2, but in 1v1 they suck. Why? Not because of the units, but because of how the resource income ends up working out for a faction that only does well in cover or hiding in garrisons. Players facing defensive Brits in 1v1 can just go cap the map somewhere else until they can dislodge them. That's not the case in 2v2 or larger game modes. Hell, 3v3 and 4v4 could even be balanced if the maps were twice as big with far lower resource income per point, but the game engine would no doubt have to be completely redone to allow that.
As it is right now I notice from my own horrible Axis ranks, and those of other players in top 200 2v2, that it seems to be a LOT easier to win as Allies. That's because at intermediate-upper intermediate skill levels, Allies are just easier to play, with fewer wipes and micro that doesn't require as much skill as Axis. I can't get MG or raketen micro right, and that's what causes me to lose a lot of games. I see plenty of other people with the same problems and who I would otherwise say are competent players and that's a different form of imbalance. The old 4-man vs 5 or 6 man squad problem is also still an issue in game modes where there is a ton of indirect fire, ie., Axis squads just end up losing health faster or getting RNG wipes, and you have to retreat a lot faster and be smarter about picking your battles when playing as Axis.
But for the top 25, I suppose it's balanced? I don't know, I tend to think top 2v2 teams would still rather play Allies than Axis if they want a sure victory, primarily because of how much less dependent Allies are on infantry preservation late game.
Exactly, that is the whole point I'm trying to make. The results of a tournament of top 20 players doesn't dictate what balance should be for the rest of the game because the average player doesn't play like a pro. The winrates are not that skewed in lower level games. Because if it were, you'd see 90% axis 10% allies for automatch wait times.