So, there's two different areas being questioned in this thread -
Alliance score - per the manual, you've got variable score and cumulative. You lose cumulative for in-alliance bankruptcies and mx fines. Variable will change mostly quarterly based on top 25 airlines in particular categories. This can create a bit of a quarter to quarter swing, especially with these nuts events that have been skewing profit margins and loads significantly.
Individual airline score - Max value is based on number of airlines in a particular game and changes elastically. Your individual score depends on your rank within a number of categories that change from quarter to quarter or so. Even if your rank doesn't change in any category, when max score goes up or down, your individual score will move proportionally with it. Individual score doesn't really impact your alliance score other than the components of individual that are also counted as an alliance score (and assuming you're in the top 25 in the game world for that particular stat)