I find the early game against double OKW extremely difficult.
It seems to be out of fashion lately, but the Kübel should not have a faster cap rate. In the early game, it already caps faster by being inherently faster than infantry.
But the good 'ol Sturmpio, Volks, Kübel combo; or even just the Kübel + sturmpio is real frustrating. Sturmpios should start with MP40 and have a mu upgrade to StGs. Early game OKWx2 is just too easy to steamroll allies (but again, this may be map-dependent or a reflection of skill level).
I also subscribe to the theory that balance is perceived differently at different skill levels. At the highest level, there may be a few builds for each faction that work right and oftentimes there is a unit that must be built at a certain time to counter another unit. At a lower skill level, the best strategy for another faction may not be employed, so that allows the opposing faction to have more choice regarding builds or composition.
This makes balance discussions difficult because there are different issues of "balance" at different ELO ranks.
Frankly, these balance discussions have been going on for years and for many they've been extremely tiresome. My favorite was on the official forums back when Scavenger doctrine artillery had no shell ceiling so it was possible to wipe a USF base and win an annihilation victory and when I made a post about it, people told me to stop complaining because I didn't need to spend fuel to re-tech...but, of course, the replay and example was from a 1v1
+1 to whoever said that people should go into the replay review or strategy section. Uploading replays is very useful and there are still people here (myself included) that will take the time to watch most or all of a replay and give specific pointers. From there (and even right after the game, possibly), you should catalogue why you lost. Was it an error in build or tech? Was it picking the wrong commander too early?
Poor micro that cost you an important engagement or a unit? Was it a tank bouncing 4 AT shells in a row?
From that point, you should look at what the issues are and address them as best you can. If you genuinely think a unit is OP, build your army up so you can counter that unit.
I've watched many of my own replays (or sometimes, a game is cast) and I can remember losses where every single grenade missed, preventing me from getting upgrades; I laid down a defensive mine too far in the back and when an early tank got shot at, it detonated the mine and that cost me the game; I've even played a game where there was no single point that I lost, it was just that I always fought losing engagements and was consistently outplayed.
tl;dr play games, upload replays here, ask for advice, watch your own replays, listen to the advice, and adjust.