Based on the limited clips we have seen, I think it's pretty obvious just how good Carey is already. I also think that he has the potential to be a major contributor early in his career at SU. His ability jumps off the page to my eye. I fully agree, you don't need ratings to tell you that.
Leaving Carey's situation aside, ratings/rankings do matter if you understand the concept of correlation, predictive validity, and the power of large numbers. The correlation between class rankings and winning has been proven in research studies. But, correlation does not equal causation. One of the common misconceptions on this board is thinking that pointing out the exceptions to the correlation disproves the correlation. It does not. So, pointing out that individual player X far exceeded or underperformed their "meaningless" ranking does not mean that rankings are not important.
My apologies for rambling on - it was not aimed at you specifically. I think your insights have added a lot to the conversations here.