ok, skill level is determined by the skill level of those you kill and who kill you. If the player you kill is a higher skill level your skill level goes up more than if it’s lower.
I think if you’re killed by a lower level player your skill level goes down more than if you’re killed by a higher level player.

That’s why my skill level plummeted. Most of the players were lower level than me and I still got killed quite a lot (especially when I was revived multiple times in enemy fire! Grrr) and the skill points I earned when I killed players was less than it might have been.