Because I don't see many midscreen ground combos:
5AA 2B 5BB jc j.5C 5AAAA 236236C.
The timing is hard to get used to, and I find it easiest to jump cancel the 5BB with 7. It feels more consistent than 8 and 9.
EDIT: Actually it seems different jump cancels are better from different characters. 9 seems better for smaller characters.