How is rank determined?

 I'm sorry if this is an obvious question, but I don't really understand. How is rank determined in Super Street Fighter IV. I know it's character based, but does it have to do with BP? I assume it has to do with BP, but when I go to player record it just says 858 to rank up without telling me what that 858 stands for. I am rank C with Cammy, but someone with 200 less BP was C plus (my plus button doesn't work). I'm just wondering what determines when I rank up.       
 
Edit: I hate the general discussion bug

BP is battle points,  these points count toward per character.   When you reach rank C, you lose BP.  Nothing before.
 
PP are player points,  no matter what character you choose, you will always rank up or lose PP points.