Yeah, basically, you have most of the answers in your questions.
What is happening to you happened to me the other way round: I hardly won 2 out of my first 8 games then got unstoppable. Like you, I'm the best in the league but not that much. And yes, I do think the game is trying to balance the interest of the league by introducing more "troll" results.
I must say it is frustrating but understandable. Look what happens to Man city or Chelsea !
Otherwise, where would be the challenge ? You are the best, you win. You are not, you lose. Boring.
Agree kingdom of demon is tanking. If he played on mobile, the game would say to him: use at leat 3 defenders or you'll be having hard times building your attacks. So the Xmas tree tactics looks deliberately foolish to me.
Overall, do not complain too much: your title is bagged which is not my case yet.