FFA Ranking

Can someone explain something to me about how the FFA ranking system works? Last i checked 343 said they were going to take rankings into account when playing other players i.e. if I’m a D6 and I play a bunch of champs and I get last place but I still did ok my ranking should go up still instead of down because of the skill gap (that shouldn’t be there, really if I’m a D6 on focused search shouldn’t I not be playing onyx and champs in the first place?) meanwhile if I beat 2 champs and some onyxs and another diamond and get first place my ranking progress goes up maybe 25% and the champ in last place still goes up in ranking. How does any of that make sense? if you’re supposed to be one of the top 200 players of a playlist and you lose to 2 diamonds why would your rank go up? Why are you rewarded for not doing well in a match against people that are “supposed to be” at a lower skill than you? The other thing is how do qualifications work? All but 2 of my qualification games were against almost exclusively onyx and champs and I did well in most of them, at least top 3 in 6-7 of them but then I get my rank and I’m a D4? How does that make any sense? Do rankings just not matter in FFA?

I think it has more to do with the number of people playing FFA more than anything else.