Trying to add a new different factor would be difficult (because I'd have to gather all the data for it), but if you decide you want
90% football attendance
30% TV performance
10% market size
-30% on-field performance
...well I'll think you're really bad at assigning weightings. But I could tell you what the results would be.
So feel free to give me how YOU would break those 4 factors down and I'll run the numbers. You want more on attendance? Great! Wishing for a world where market size doesn't matter? I can do that