Possession - Need an explanation

Simple question.
How does it work? I am struggling to see the correlation between the skill of the players, and the positions they are playing in to the possession that the team has.

I have a game where I've got five midfielders of 5-6* against a team with just three central 3* midfielders and they've got similar possession which doesn't make sense.

In my champions cup final today, similar story five 6* midfielders against three 5* central midfielders and it's again 50/50 possession. Does the possession have that much of a bearing on the match engine? And surely playing three central midfielders leaves you vulnerable to an attack down the wings, and doubly so if they are attacking wide midfielders, no?

And surely a red card would have an effect?
I played against a team with a 4-3-3 formation and they lost a central midfielder to a red card.
At that point it was 4-4-2 v 4-2-3.

Four 5-6* midfielders with wingers, against two 2* central midfielders.
Possession 61-39, which was the same at the start of the game with their other 2* central midfielder. And in my champions game today, it was 52-48 against three 5* midfielders. That doesn't make mathematical sense.

Everything listed up there afects possession..I don't know the exact numbers but i've noticed that playing against 1-2* lower team gives you possession boost..
1 thing is sure, possession is not only afected by midfielders.. a while ago more ppl in midfielder position would give you more possession, aparentlly they've changed it now..
Red card should be 5% possesion penalty or smth like that.
The best way to get more possession is:watch ur games, get supporters to watch yours.. u'll have 15% boost and u'll see 60:40 most of the time.

Also make sure ticket price is correct- 5% possession bonus for home match helps alot and i see many managers having 1-3% possession cause they set high ticket price.

Yes, the numbers I've given have taken into account the attendence and friend boosts. Those are the absolute values.
This is a not a question about how other factors can improve possession but why a three central midfield formation seems to give an inordinate amount of possession despite the players' abilities.

Can someone even answer the fact that a red card does NOT seem to change the stats (that's got nothing to do with the amount the stadium is filled because that's an in-game scenario)?

Whenever i had a red card i lost about 5% of possession.. ofc it depends, if i get a half time it would be 2% or so..

What i think about this is.. All players in yellow( MC-ML-MR-DMC-DMR-DML-AML-AMR-AMC ) should afect the possesion in the same way, not just the MC.. so the more players in yellow you got on the pitch, the more possession you get.
Maybe 3MC formations get boosted cause they've got AML/AMR or DML/DMR to play next to them ? uh idk.

I think that 3DC-DML/R 2MC-AML/R ST would give the maximum possesion boost as it has 6 players in mid positions.

possession is an urban legend...