Letter grade instead of "Yes/No"

I think it would be better if, instead of a straight up "Yes/No" reccomendation, it let us give a letter grade like A B C D or F. This would let us give C's to providers who might not have done anything wrong, but didn't really do a great job either.

Or if not that, at least a "neutral" feedback like ebay.
After you have submitted a review, you will see a "edit" button which is available for a certain time period after posting a review. In edit mode, you can put anything you want as a recommendation. It is still important to have it reflect either positively or negatively, so that those who may not have premium access can still know if you recommend whoever it is you are reviewing.