here is something I discovered recently debugging a mission:
at the start, my player rating was 7500, it went down when I, as group leader, lost a group member. It went up when I killed an enemy.
Hope this is useful to someone, it help me debug my mission...I duscovered this by calling this script:
#start
player sidechat format ["my rating is %1",rating player]
~2
goto "start"
great for debugging!