Yeah, I really don't understand the ranking system but it seems popularity has a factor and I suppose wins are not all weighed the same.
I don't think it's been explained well anywhere but on last night's Dark, Excalibur did mention that who you beat means something. I like the idea that simply beating a bunch of jobbers doesn't necessarily get you to the top (and beating a high seed opponent should matter).
I feel AEW is purposefully not explaining the rules so they can change things as they go along.
edit: Does Brock Lesnar even wrestle non-title/tag team matches?