How does highest skill work in Halo 3?

[SportsRuleTheWorld]

When does it go up and when does it go down or is it just random

 

[Disco Stu]

It's to do with how many games you win, but also how consistent you are within those games, so if you win loads of games, but it's just because you were on good teams and you got hardly any kills, your skill level won't go up