Not sure on what basis you say that EU servers are fine.
Playing since season 7, in mid teen seasons switched to NA East/Central because I realized that game was playable on 100-150 ms ping when EU side was sleeping (past 1 am). But this season was the first EVER where I intentionally skipped playing EMEA server and went almost straight to NA East / Central because exactly the same experience Blekerodo is talking just in ranked. Starting from D4 lobbies basically 4 out of 5 games top 3 to top 5 are dominated by Preds/Masters who should not be there (matchmaking topic) and smurfs/hackers who clearly can't play the game legit way.
If I could post names, links here you could be able to see my latest 20+ games but the quick summary is:
- 1 1st with 7 KP
- 3 3rd with 0-5 KP
- 2 4th with 0 KP
- 4 6th-8th with 0-2 KP
- 15 9th or worse mostly 0 KP
And that's me (previous split D2 almost D1 playing Plat lobbies). Matchmaking is one thing but clearly smurfing/hacking is the biggest/huge difference maker between those sudden "pop-offs" with 3+KP games vs losing pretty much first fight on landing or when holding rotation in end zone(s) = only/mostly hacker teams alive.
And you either agree to this statement or you can try proving the magical difference between 4 games out of 25 where I am competitive vs 21 games where I am basically bot suddenly within same 4-8h game time :)