I can confirm that too. I always take a look after every match, and there is NO, nada, 4% for MotM.
Alongside with that, dunno if it's a bug or it is a limit : when you are supported by more than 1 friend, you don't get extra possesion %. It remains at 15%, no matter how many ppl are supporting you. This happens no matter if you attend the match or not - 15% no matter if 10 or 100 ppl are supporting you.