Yeah, I wasn't very clear. Sorry. By open ground I meant in the middle of a stage with ceilings.
I am gonna turn the game on and find out a few things.
4F+K does cause a wall splat so that idea is out the window.
214P 4F+K should be guaranteed.(214P gives plus 34 unholdable sitdown, and 4F+K is only 22 frames.) This will only hit if there are no walls nearby though. For around 142 damage with juggle and walls. Izuna 214P shoho is 131. Izuna PB is 140.
Also I used Tekken notation with the CB_Shoho_Juggle_PB. The _ means or. I like to use it since you can say a lot of options or mixups at once. I am kinda used to people not following that, I really should get better about it but I think all fighters should use it.
Another thing Is normal Izuna into qcbP into 4F+K does put them in max threshold for a CB. The thing is they can block the CB. If Ryu got any new sitdown stuns chances are he could have a guaranteed CB on everybody on a normal ceiling Izuna.
Hope I cleared some of it up at least. I have been known to not make much sense hahahah.
Edit. I thought 4F+K was a real sitdown stun that just sucked due to slow escape. It turns out even if they don't SE they can hold moves that are 14 frames or slower. So even with the SE glitch 4F+K is pretty worthless. So yeah, anything with 4F+K isn't reliable.