Any grade is going to be inherently flawed because it involves human error. Grades — in football and in art class — involve bias, opinion, and arbitrary nuances that should immediately give you pause. There is no site on the internet that gives grades that matter beyond whether or not you want to agree with that site’s opinions. The same will pretty much always go for rankings too.
Now a ranking based on grades, that’s really something special.
A website that I don’t need to name or link to recently published an article in which they ranked the Seattle Seahawks as having the 11th-most talented roster in the NFL.