class ActiveGenie::Ranking::PlayersCollection

4 rounds to reach top 10 with 50 players
- 14 eligible, tier_size: 4
- 24 eligible, tier_size: 10
- 35 eligible, tier_size: 11
- 50 eligible, tier_size: 15
Example:
based on the eligible size, start fast and go slow until top 10
Returns the number of players to battle in each round

def tier_size
  [[(eligible_size / 3).ceil, 10].max, eligible_size - 10].min
end