Group By value with Average aggregation calculating differently

Hi there, 

I believe I'm missing what is going on with my various attempts to Group By source data in order to gain an Average aggregate of a score. I take the entire dataset and when I place it in a table card and AVG the score, the calculation is correct but anytime I use the Magic ETL I was presented with a different value and yet a third value when attempting SQL.

What am I missing? 

Thanks!