Scorecard: set score where no data exists

We want to have as many scores set as possible on all our accounts.  There are some instances where a field is blank or is not eligible yet, but we want a score.  For example: Customer has never submitted an NPS or is too new to have cases.  I tried setting the NPS score based on null value....no luck

Is there a way to do this? Otherwise, my backup is to add it to my rule that essentially defaults all the scores