So would it be fine to you if the POINTS change algorithm was also secret? If the rules just said "points will change based on players' performances"?
Would you then say "points ARE predictable. They are based on goals and assists. There are some other parameters but goals and assists are about 85% of the points"?
So would you be happy if you had to predict how many points you might get for a goal? If the rules just said "points will change based on players' performances", so you could figure out you probably get some points but you didn't know for sure how many points exactly.