I’ve messed with this as well, and I’ve come up with two “possible” reasons. The headstomp has 30 frames of start up if it takes more than 30 frames for you to counter the fireball it won’t hit [unless you use the appropriate distance short, foward, or RH i.e. depending on the distance between you and your opp.]; However, if you time it as a REVERSAL it hits 100% of the time (from testing w/AE and it obviously says reversal in screen). An alternate method is to use the DevilReverse +UpTwd +Jab and then Jab to do a quick DevilReverse although this requires a fair amount of timing in itself and rarley hits (b/c it’s hard to hit the opp. b/f there back in neutral). Another possibility is that since the headstomp immediately hits (where as the DevilReverse hits only after putting in another command) the cpu might not be able to distinguish between the fireball and the opp.
YBH: pg. 171 explains part of your question. For the j.Fd, j. RH the time at which you hit the button determines whether or not it will cross up. This has to do with the hitting frames and hit boxes. Short has the shortest amt. of startup frames 2, as compared to 3, and 5 respectively for fwd and rh. Plus the short will always hit as a crossup depending on distancing over opp. The downside to the short crossup is the hit box is smaller than the fwd and rh are. Since you use a crossup to combo I don’t see why mixing up stun length would have any usefulness.
If any of this is wrong or confusing please let me know.:wgrin: