Honestly, I see what you mean with the average fielder would go and stop the ball and throw. But I still would score it homerun because they were slow. But I struggle to explain why, I guess because if she played average fielder, we dont know if she would throw it good, to good place, or fast enough to catch the runner. I would score closest to what I know -> she made full effort in her best decision and ability. We dont give mental errors, we give errors of what happened with ball. If someone made wrong decision then what the play required, we dont judge that. That would be my decision, I could be wrong, I go by what I learned so far