I'm going to be honest: Season 9 probably has the best potential to climb ranks of ANY Season, simply due to math, and the ability to choose the right play style, even with said autofills/trolls.
Why? If you play fill, and the rest of the community plays a single role, The Single role players who are successful are climbing at an exponentially faster rate than the "Fill" players.
That may sound like "Fill" players are getting the raw stick, but in reality, it's a MAJOR GIFT.
Fill Does reward more LP both to the role you get, and to the Splash. You get 6 splash for a Win. You lose 3 for a Loss. By Default, Fill is actually more "RELIABLE" to climb with than Single role, even if you end up a 50% Player, who wins 3 splash and loses 3 splash, and still gets autofilled or secondary role picks often enough.
But there's a hidden advantage that hasn't existed before:
As Single Role players who are successful climb faster, all that's left behind are the bad players, and the Fill players. The Fill players are arguably just as good if not better than the Single Role players, The Fill players are realistically fighting people 3-4 tiers under them as the single role winners filter out!
For the first time in League - Ever....... they have actually created a smurfing mechanism which helps players climb reliably.
Just look at my account. I'm around 70% Win rate right now as a "Fill." I've only went up about 1 rank across the board.
BUT...... I am systematically going up without win/loss randomness. My LP gains per game are also rising a lot. I'm almost to the next round of promos one day after the last, because my splash/win rate is pushing me up.
Whereas the Single Role Player is going to Yo-Yo back and forth, I'm not. I'm going to just keep rising.
And if I get to a point where i'm winning 50-50, I'll still be climbing.
In other words, If you are losing a lot right now..... Your choices are part of your fall. Make different choices.