Well, all the instructors agree that she should be second grade, and he who spends a lot of time with her should know better.
That said, when he showed the rankings he mentioned "By my guess, this is where EVERYONE stands", so it very well could be that his guess was only for the other school solely and went with official rankings for his school. I had interpreted it as he was assigning levels to everyone, including Maki, based on his experience.