Unfortunately, formatting the data as a table is still giving me the wrong result. And I haven't been clear on what the data is I'm interested in.

Yes, I did manually hide each row that was for an NL player. So league affiliation is already accounted for. What I am looking to compute is exclusively in the AB column, with the header "Final D score". In this column I need the average of the values that are not hidden, and the standard deviation of these values. When I entered AVERAGEIF (AB3:AB97, TRUE, AB3:AB97), I got a division by zero error. When I entered AVERAGEIF(AB3:AB97, TRUE), I got a division by zero error. AVERAGE results in the averaging of both the unhidden and hidden cells in column AB.

Do feel free to muck about with the sheet. Anything you do I can cut and paste into a larger sheet with more values, or just to see it would tell me what I needed to do to apply it to the full sheet