Changing a unit's rank using either setUnitRank or setRank will also REPLACE their current rating dependent on their new rank (colonels have a rating of 7500 etc).
That is to say REPLACE, not add to: the unit's old rating will disappear with the rank change.
Waffle SS.
Behavior when used on players in multiplayer seems unpredictable. (Arma 3 1.00)