Don't know much about recruiting, but the ratings seem very sticky/laggy to me. Players will start to get a lot of buzz, tons of majors will get involved, and then like MANY months later their rating will get a seismic bump. Like Markelle Fultz and Jon Issac in this class were middling 4 stars and then every major school was on them and them and anyone with a twitter account could tell they were HOT. Then many months after this they are finally bumped to top 25 five star recruits.
And then on the other end you have guys like Doral Moore, Kwe etc. that are struggling a bunch, not getting as much interest. They will stay with a high ranking for a long time and you will eventually see their ranking tumble on tape-delay. It seems like it's to the point where you can't even just look at rankings exclusively, you have to kind of consider a hybrid of 1. Their ranking and 2. How they have been doing recently, their recent buzz from scouts, what schools have been around lately, etc.