But since a picture says more than a thousand words: Try zooming out to the full time range that coh2chart offers. About a year ago (actually the 21st of June, 2016) there was the last big patch before the WBP. It incorporated various changes, most notably the introduction of the US mortar and a serious buff to Penals.
Here is how this looked like in coh2charts (4v4, 500+):
Now, coh2charts only goes out to one year, so you can just see how this looked like before: OKW on top, SOV at the bottom, everything else in the middle. The the patch hits and BOOM allies OP. It took a little more than a month before the old status was restored (yes, there were a few hotfixes to bugged US abilities and a slight toning down of the USF mortar, but the allied win rates were still high when those minor changes hit).
This spike for one side or the other will always happen when there are significant changes but they are not really an indication of balance but rather of a change in balance.
That said, what coh2charts does show is what player in these ranks on average experience, and while this likely is a temporary effect due to adjustment of the ELO, they are likely not aware of that and perceive it as "Waaah, my faction is broken!". And this is a valid concern. In fact, every significant patch comes with the danger of driving away very casual players. E.g. the guys that brought me to play this game, now play maybe once a month and I hear stuff from them like: "Well, they patched my IS, I can't use them anymore."
Rather gradual changes would help to alleviate both effects and also would make balancing easier I guess, but the issue then of course is that in reality this would mean we'd need a lot of patches to get anywhere, which likely not going to happen...
So, to give this post a little more on-topic spin: Significant changes to e.g. the Elefant might result in many casual players to get alienated (and I would content that these game modes do attract a lot of casuals) so I feel you'd really have to be careful here. Yes, certain units and abilities might be cheesy, but the players playing now do so despite of this. The danger of not fixing this is that people will get bored of the cheese and leave, but others might leave because they can't follow the changes. Tricky...