As an app developer who has gotten those reviews, the reality is they don't actually matter. Since everyone gets them, the real question is how many happy and 5 star reviews you get from the rest of your customers. You don't have 3 stars because of the guy that put 1 star, you have 3 stars because of the people who gave it 3, or all the people who didn't feel it was worth it to put down 5 stars.

The situation is the same here, at my school when viewing aggregate evaluation data, I find it to be VERY accurate to the actual experience I've had in those classes, and I think that's the issue here. Yale is protecting teachers from being called out for being bad teachers.