Differences in Hakan's vulnerable hitboxes when crouching.
Moreso than any game in the Street Fighter series, characters in Super Street Fighter 4 move around a great deal even while not receving input (or minimal input, in this case).
For the most part, the vulnerable hitboxes (i.e. the area that can be hit on a character by an opponent) remain the same during this animation.
With Hakan however, his crouching animation changes his vulnerable hitboxes considerably.
Hakan's crouching animation looks like this (this is at 20% of the original speed):
The change occurs over a relatively slow time (approximately 26 frames) and it's pretty subtle if you aren't looking for it. However, the change adds a massive randomness to his ability to be hit while crouching in certain situations.
This is the capture of Hakan when the hitbox occupies the least vertical space in the animation:
Compare that to the vertical space occupied by Hakan's vulnerable hitboxes when they occupy the most vertical space due to the vulnerable hitboxes of his head poking above the vulnerable hitboxes of his body):
Because of the hitbox for his head extending above the hitbox for his body, there are approximately 12 extra pixels of hitbox that can be hit. Given that the image from a 720p video, it means it's a difference of approximately 1.67%.
What can a difference of 1.67% make?
Overlaying the hitbox image for Makoto's cr.HK (which hits high) over the hitbox image for the point in Hakan's crouch animation where he exposes the smallest vulnerable vertical results in this:
As pointed out by the area highlighted in light blue, it can be seen that Makoto's offensive hitbox (in red) does not overlap Hakan's vulnerable hitbox (in yellow-green); Makoto's cr.HK will whiff in this situation.
Compare that to overlay of Makoto's cr.HK over the hitbox image for the point in Hakan's crouch animation where he exposes the largest vulnerable vertical hitbox:
This results in a very different outcome, as pointed out in the area highlighted in light blue; it can be seen that Makoto's offensive hitbox overlaps with the vulnerable hitbox exposed by Hakan's head, resulting in a hit.
It's more than likely that there are other moves in the game that will hit or whiff a crouching Hakan depending on the frame of animation he is in during his crouch.
