As far as I am aware and I really think that I am 100% right, you get that 15% ball possession but is more likely to be cosmetic (well a part of it) because you actually won't get a real value of 15%. I guess this is easy to test it as well, just take 2 teams same quality, create a 15% ball advantage and yet you will see that the difference would not be of 15% in ball possession.
Regarding this "weaker" friends. Top Eleven said there are more then 150 million accounts so a minimum of 75 millions of games per day but there are many more, who do you think can control this loosing on purpose? For sure it happens because that's why friends are for . Joking but is reality...
I occasionally get matches where I am descended upon my hordes of visiting fans - one such match was today in the Cup:
Opponent was a Level 5 manager, won the Treble last season, obviously plays a lot with these friends, is in an Association with some of them.
Stats from the match - 11% away possession certainly told, but my 3% better 4-3N-3 vs his 4-5-1V was a tactical advantage.
Any formation or tactics advice given is based purely on experience with my teams...
This is a game on social media. It's working as intended.
Season 71, Level 61