@16bit can you go into detail on the cage mu?
She controls the MU except point blank. First he has to get past her zoning with IAF then he has to get past her footsies. He can only beat her footies by taking a huge risk or hoping the Kitana screws up. If she hits him she does half life and is back to keep out. If he's right he either does decent damage into pressure or more likely is just in and has her blocking and begins his game. Obviously once he's in it swings to his favor but her tools for dealing with it are pretty good. Her d+3 can go under f+3 and linking normals into Ass is good for escaping.
I have seen your brother play the MU against Dizzy in tournament. His biggest problem is his overuse of d+1 to get out. Dizzy will often stop his pressure and if you try to poke out with d+1 you're getting lit up. He also will interrupt d+1~cutter because it has a gap. You cannot use d+1 as your main way of getting out. At this point I only use d+1~cutter against him for two reasons. One is if I am pretty sure he's going to do a high(like if I read throw or 2,1 after an EX forceball trap) or...if I just want to check if he's having an off day and not on point with his counter poking lol. You need to use d+3 to poke out. That way if he counter pokes it's not a punish you just have to block the f+3 and if you're right and poke out you get advantage and a mixup.
Also what a lot of people don't get about the Cage counter poking metagame is that he can't be waiting to counter poke AND continue his pressure. When you're fighting a Cage that is looping f+3 and stopping for counter pokes it means you can now try to jump out, walk out or even just throw him. When you fight Cage and you're in his pressure you cannot be scared and freeze up. So many people do this, even the top players. The guessing game is heavily in his favor but you must play it. Otherwise you'll just lose.