The combat score is a composit score consisting of Historic Score, Tourney Score, and Ranking Score. The basic formula is:
( Ranking Score * m + Historic Score + Tourney Score * 2 ) / Clan Age
Adjustments:
If 14 < Clan Age < 140, then substitute Historic Score with: [ ( Historic Score ) / RoundDown( Clan Age / 14 ) ] * 10
If Clan Age < 14, then substitute Historic Score with: Tourney Score * 10
The multiplier m is chosen so Ranking Score is worth approximately as much as 4 Tourney's Scores
Arguments:
This formula is biased toward eldars becuase it includes historic score: The historic score is basically an average of your last ten tourney scores. By adjusting the historic scores of clans that have played less than ten tourneys, this bias is removed.
This formula is biased toward eldars becuase they generally have bigger titans and can score more points in a tourney. By dividing the sum by the Clan Age, this bias is reduced.
This formula is biased toward younger clans because the sum is divided by clan age. There is a definite advantage to having a smaller age, but the actual advantage is greatly reduced because older clans generally have larger titans and can usually score more points per tourney.
This formula is biased toward very young clans because their historic score is replaced by ten times their tourney score. Probably true, but not very many clans that are this young will score enough points to make it to the top of the ladder. Those that do will definitely be worth keeping an eye on.
This formula is biased toward ranking points. True, but ranking points are much more important than regular points. If you score enough points during each of ten consecutive tournaments, you can make it to the top of the ladder without any ranking points. Lots of ranking points just makes it easier to get to the top.
It would be better to divide by the number of guns instead of clan age. Nope. Dividing by the number of guns seems to balance the bias of age, but that means you are actually measuring the number of points scored per hit. Always shoot at someone with higher shield tech than your weapons tech and you'll score higher. Plus, the number of guns a clan has is not information that is available to all players.