The author only lowers stats if individuals have gotten weaker over time (he mentioned as such). He doesn't lower them because they don't gel well compared to later characters. There is no evidence Rankai has weakened so his stat has remained the same. Yet just look at his fight with even Shunmen keeping up and wounding him, and you will see that Tou calibre fighters would decimate him because of his stupidity and lack of speed.
^And as for beast Bajio I am fine with putting him in A- as he has bound to have improved since last we saw him. But in Yotanwa's tier he is definitely not.