Basically the ice clone is more broken than the freeze and sets up more damage, a variety of 100% scenarios. Mix this in with the absence of jump starters and other slight modifications to gameplay, makes Sub a bit better than Kabal overall.
The collision detection on his spin move is too small, it's similar to MKII where it's a lot easier to hit someone if they are doing an attack but it doesn't have to be that way. Also, the spin pushes him out of the corner in MK3 cutting off infinite potential. This should have remained in UMK3 and it wouldn't have made much of a difference really. Anyone who can really use Kung Lao doesn't need his corner infinites but can do his mid screen juggles. Another thing about the spin in MK3 is it doesn't activate damage protection, so if you are able to connect it, it only takes a few hits to beat someone. Basically UMK3 beefed up Kung Lao into the higher end of the top tier.