Dominion - Combat Score

In the Dominion game mode, how does RIOT calculate a player's Combat Score in the post-game screen?

I routinely score significantly higher than my allies in combat score (as shown in the attached screenshot), however I do not always deal the most damage, tank the most damage, or have the best K/D/A ratio. The screenshot game, for example, I had the second most kills, second fewest deaths, did the second least damage to champions, and tanked the 3rd most damage from enemies, and earned 3rd most gold on my team. I also spent the second least amount of time dead, on my team.

In some games, this pattern is inverted, as well, where I will have done more than my allies, but my combat score is low.