Optimum and Polish Eagles had the same points in the last season. But why Polish Eagles got the 9th rank and Optimum got the 10th?

there was a forum post about that iirc but I can't find it, you should ask TR-8R in your clan, he did most of the research on this

fizzer said tie breakers were based on clan ID, there is some weird equation like clan ID divided by number of players and whichever value is better wins tie breaker? fizzer even said it's not ideal but no reason to change it iirc

from what I remember fizzer didn't even remember that's what it was in an ama

In my opinion, the clan with the higher CW rating should be ranked higher in such case. Clans with higher ratings had to play against tougher opponents to get the same points.

And with such benefit of high ratings, it will help prevent clans doing suiciding tactic to lower rating at the end of each season to get better matches in the next season.

it probably uses whatever order they come from the database, which is depending on what DB WZ uses and how the tables are set up

iirc there was indeed a forum thread about this, sadly WZ is blocked at work so i cant search it atm

I did a quick search on the forums as promised, all it finds is an AMA thread from the Clan Wars update.
Fizzer says in the AMA that he doesn't know...
https://youtu.be/Q29lEvWUm08?t=1140