SMH.
I guess according to the JBBS thread, Ragna dropped to A tier because he was trouble creating situations in which he gets damage. In other words, he gets his damage based someone's mistake (not blocking high/low correctly, jumping out at the wrong time, getting footsy'd). Let's also not forget that his pressure game, while pretty solid, only lasts so long before he's pushed out too far, and it's also completely ruined by IBing. In addition, he has a hard time turning random hits into solid combos, unlike Bang and Litchi.