Board Game Arena

I’m a pretty active Arena player as I love the competitive aspect of it but I am struggling to understand how the number of tiers are assigned to each game. I see a general pattern such as games that aren’t played as much usually have less tiers than a more popular game but there are some inconsistencies.

For example, a game like Seasons which has about 1,000 active Arena players this season has 6 tiers while Splendor, which has almost 5x active Arena players this season but only has 4 tiers.

Is there reasoning or an algorithm behind how the number of tiers are assigned each season?