IF 1000 games are played with axis and 500 are played with allies in the top 150 players, that means that axis played 500 games against players who are outside that skill bracket. Which means that axis will have an inflated win rates because they are playing against weaker skilled players.
Doesn't that mean you are assuming that all 1000 and 500 are seeking concurrently? RL doesn't work that way. The raw number of games played doesn't say anything about when they were played or what the Allied skill level was like when it was played.
You're making several assumptions including that the pools of top 150 Axis and Allied players is mutually exclusive and that all the top 150 allied players are all hoping on the OKW seek bandwagon. How can we know that the top 150 Allied players are seeking in such short supply that the top 150 Axis demand always exceeds the Allied supply? It's also possible that the playtimes of Axis and Allied top 150 varies enough ELO matching is still close enough.
Even if we concede that Axis Top 150 demand is indeed exceeding supply then ELO matching still applies and we would assume that the person matched is still as close as possible in skill level. Are we going to argue that the skill set of a top 150 player vs. say a top 250 or 300 player is such a wide gap that it precludes OKW faction strength as being a contributing factor if not the main factor?
I don't think so.