Some people ask us why we don't just ignore blanks entirely and then advance the two candidates with the highest average scores to the runoff. Others ask why not allow negative scores as well with the default being 0. 

In STAR Voting, blanks are counted as zeros and the two highest scoring candidates advance to the runoff. Having the lowest possible score be the default ensures that voter intent is preserved and ensures that the voting method is not giving an unfair or unintended advantage to less well known candidates.

The five star ballot and the STAR Voting rules are designed specifically to ensure that voters' votes will count the way the voter intended them to, by helping the candidates who voters explicitly chose to support beat out the voter's less preferred candidates. 

For the purpose of determining the finalists who advance to the runoff, if a blank was not counted as a zero, and if the average score was used instead of the total score for each candidate, then the system would give relatively unknown candidates with a few strong supporters an unfair advantage over well known candidates with a much stronger supporter base. This is why blanks in STAR Voting are always explicitly counted as zeros.

For the purpose of post-election data analysis, the number of candidates left blank, vs those explicitly bubbled in as a 0 does provide some additional data that could be interesting for campaigns, and could be published as part of the full election data analysis.