Not really, there is no evidence to suggest that they wrong, especially in finding optimum power level for infatry fights.
There is.
You'll find existence of this thread being full of evidence over last 5 years.
The fact is that game is in better state has probably allot to do with the number of RNG, Cheesy and Bugs that have been fixed and less with actual balance decisions.
RNG has very little to do with infantry combat, unless we're talking about the brilliant, non working cons that were design supported by your personal guru of balance who doesn't work for relic for over half a decade.
When it comes to balance homogenizing faction made balanced allot easier.
By homogenizing you mean taking away cheeze based tools and replacing them with reliable ones, like USF smoke and mortar or replacing kubeljesus with actual HMG?
Finally even if one accept that "balance" wise things are better that does not prove that everything at that time including optimum power level was wrong.
The "optimum power level" doesn't take into account what's standing behind the unit and units place within the faction. Current approach does.
To me, that's pretty concrete proof that "optimum power level" approach is flawed at its core philosophy - it was created with 1v1 vacuum scenarios, which we all know serve little purpose in balance discussions.
I can give you plenty of examples that went horribly wrong in the in the last patches and that does not mean much when it comes overall balance.
Subjective opinion on the direction of changes does not equal a factual evidence of "something going horrible wrong". Design-wise, things improved overall, the numbers behind these design decisions not working perfectly as intended in the first iteration on live are completely different subject.
Bottom line is that last patches have increased the power level of units for no apparent reason leading in vicious circle.
Which units?
The out of meta units were buffed to the point, where they are appealing alternatives, like RETs or M5 quad.
Out of infantries, there were only toning DOWN of units, like con weapon slot limit or bren nerf.
The patch notes of last couple of patches do not seem to support your claim here.
For example :
Ostheer T4 become early accessible then M36 had to buffed and now 3 Tiger come allot faster than rest of Super heavies.
Correlation doesn't equal causation, if absolutely nothing happened to ost T4, jackson would still had to be buffed, because OKW still existed at that time. USF always struggled with heavies and panthers and zooks or their AT gun clearly are not up for the task.