It sounds crazy but I honestly think that OKW players now started to lose more cuz they are low skill in general.
What I mean is before last patch they were playing blatantly OP fraction. Now when the fractions got more balanced they just cant adapt to play with oponents that have equal abilities.
Did it ever cross your mind that in 80% of cases the same players playing OKW are playing at least one of the allied factions too? Hardcore nazi fans with no interest but in one faction playing exclusevely that faction are not the majority of okw players you encounter.
Related to "adaptation" I can explain this issue, because I generally like to play OKW next to ostheer and USF (I hate soviets but I still playing them from 2 reasons: 1. 50% of game's initial price was for this faction; 2. I could not argue on forums if I wouldn't know about this faction ):
Before latest patch, there were cheesee tactics that people were tempted to use because they were making things easier for you (less micro for instance). Besides these tactics there were others, harder to use, but effective nontheless.
After latest patch, when OKW was nerfed, the cheesee tactics remain the only ones viable, if you want to win, of course. Anything else you do, you are next to dead. So now, these cheesee tactics are not only easier, but necessary, and they are still failing in almost 50% of cases.
So, the "lack of adaptation" you accuse it's in fact THE adaptation to what OKW currently is.
From my point of view, I am not complaining that OKW is such a bad designed faction. Its initial design was not bad, let's remember they had the same penalty for fuel AND for amo. It had a few units that somewhat overperformed making fuel and amo penalties to feel like not enough. Those units needed a little tonning down and all would have been fine, keeping the initial resource penalties.
To give you a little example: the first raketen nerf was too much. They should have kept raketen as a reliable AT weapon and kept the 66% amo income percent. That would have forced OKW to COMBINE its shrecked volks (that were not enough) with the raketen. And so on.
But what Relic did? They started to nerf left and right, then felt bad about it and increased the amo income to 100% (hello shreck blobs) then felt even worst about it and nurfed the amo income to 80% still not solving the problem of cheesee tactics and still modifying and nurfing almost every OKW unit.
And what we have today, it's a product not of a bad design, but of a bad management of a faction that forces you to play in 2-3 ways at most, or suffer defeat. Nice.