I say that it is not completely random and to an extent our action matter a lot, the problem is that there is a big % that seems to not consider anything we do and is often based of luck,troll and other things that make no sense especially to me, like the fact that abandoned teams can be competitive enough to grab a good result against you.
The game considers I think many things the number 1 I think is the draw (this is why so may resort to manipulation). Skills are important but not if you are in a plus 2 level CUP/CL. If you end up in the right draw, even 1 level higher than yourself but with teams with similar quality TE is actually a very entertaining and almost fair game.
I say the key is the Nr of good players that you have on your team not on visual skills but performance (nr of goals,assists, good defenders etc.)