I think you are missing a point here n there about how systems works for each game, including CoH.
https://www.coh2.org/news/54445/the-ladder-1v1-matchmaking
Most if not all games uses different types of ELO system, whether they show it or keep it a secret number. Rank/divisions are just a way to give players some kind of feedback on where they are ranking compared to other players and give them some sense of "progress" or objectives to achieve.
When you have a big playerbase, SEVERAL THOUSANDS active players at any given moment, you can take the luxury of putting restriction based on leagues despite MMR discrepancies.
In the case of CoH, you have an ELO system which determines your ranking and the level tells you on which percentile you are within a faction. Top 200 onwards gets lv from 16 to 20. But 201 and above, that's not the case.
A faction requires 4000 players to have properly all lvs distributed. Factions with less players will have missing levels.
Accordingly, faction balance is almost irrelevant in this respect, because imbalances are compensated by matching with a better or worse player. Obviously, this does not work for the top players, as "better" players are simply not available (another reason for balancing from the top).
Thanks for bringing this up. There are certainly better ways to show skill level than absolute ranking or an artificial level 1-20. I think a good way to measure if a faction is up or op is to see if the matchmaker consistantly puts a factions 80th percentile player against let's say another faction's 65th percentile player in a match that should raise red flags. It would mean that the first faction is underpowered since a more skillful player is consistently pitted against a lesser skilled opponent and still have a competitive match. The only way this goes wrong is if there is ample evidence that the average player of one faction is simply better than the average player of another faction.
The ranked playerbase has shrunk throughout the years that you don't really have a proper way to qualify how much better a certain percentile of the base is compared to one or another. Even the arbitrary top 200 have fallen short since a year or 2 ago.
Add to that the CoH ELO sytem is "exploitable" in the sense that basically "ANYONE" can rank top 200 through a small sample of 10/20 games by playing against potatoes or by spamming games and having a W/R above 50/55.
Gauging "balance" through matchmaking is a joke, because players are not restricted from playing against opponents which are much better or worst than them. CoH2charts became relevant only when the difference between factions was at +10% or more on WR. Even worst, the site was a general faction performance which had no information about the specifics match ups against each other.