The problem with those school rating web sites is that anyone can post whatever they want on them - regardless of whether they have any real experience with the school or not. Even if a person is familiar with the school, does that persons experience mean that it will be the same for you? Not at all!
Sorry to sound so contrary on this matter, but buyers tend to look for short cuts in order to find the "best" school for their children. There are none.
You know your child better than anyone, right? You love your child more than anyone, right? So why would you entrust your child's education to anonymous people?
To find the best school, you can visit that particular schools web site. Take a look at test scores and the services that school provides. (Maybe your student likes a certain sport, or music, or needs special education support?). Then - pick up the phone and call the school. Ask for the principal and chat away. If you live nearby, make an appointment (well in advance) to visit the school.
I know this isn't the specific answer you were looking for, but James Madison might be a great school. Someone may have just had a bad day or one poor experience and the entire rating goes down.
Give this some thought.