I can’t recall where the posting was right now.
This is version 2 of the new match making system.
At first to counter people with an overleveled Thor your highest level dino was counted most.
Stat Boosts and Trophies were said to be a factor.
This was to stop arena dropping because if you dropped down then switched to a super stomp you team you wouldn’t be doing much stomping.
In the second version because people complained about being punished for leveling up (they still do) the average of your team is considered and some mystical score is generated based on dino rarity and stat boosts. Trophy count is still supposed to be a factor.
It’s rare but you will, once in a while, see a resurgence of things like a level 30 Suchotator (Rare) or even a level 28 Miragaia (Common) because they don’t hurt your team as much as having a level 25 Diloracheius. Once in a while you’ll see a level 11-15 Dimodactylus amoung such high level things as people try to figure out how to lower their team level and yet have the thing do something (swap in bleed) if it is drawn for battle.
Edit: The actual Algorithm was never posted just a few scant hints.