Unfortunately, nothing in the book states that's how we have to look at the ratings. I imagine Horikoshi just doesn't care about how strong a certain character is unless it comes up in the story. He probably didn't even write this all at once, and I doubt he was making sure everything was consistent with who scales to who.
Though Hood is way too blatant, I don't understand how you can rank him slower than Hawks and Endeavor so maybe that has more merit than I think.
Cementoss is B+ while Tiger is labeled as A, I don't really see how that makes sense considering Tiger has no strength enhancing Quirk. Unless this means his physical strength, but that'd be weird since Cementoss isn't shown to fight physically. And his B+ is slightly higher than Geten's B, which is actually consistent since he beat Geten.
Tiger and Magne scale to each other, which means Magne B strength is equal to Pros A rank?
Aizawa is Rank C, stronger than Gran Torino who is Rank D. So anyone who is D rank or above scales to Gran Torino, and
is capable of this? So Aizawa can break concrete like this, along with Edgeshot, Hawks, Vlad King, and Snipe. (I doubt Snipe's rating is for a gun, but I guess pistols in MHA can do this)
Like I'm ignoring calcs here, and this doesn't add up. Since even Ragdoll is apparently comparable in strength to Gran Torino. And it's really weird to assume this doesn't mean his Quirk, since he uses his Quirk for propulsion to increase the power of his attacks.
Yeah we have to jump through way too many hoops to make these ratings make sense (Still has problems), and I doubt they were made with serious scaling in mind.