Angle Calculation on ROB's dsmash/uair

[AntiPrompt]

I picked up ROB recently, and I've noticed that the knockback on his down smash and up air behave unusually in that they seem to send the opponent on a different angle in a 90-degree spectrum every time it hits. I might guess that the trend, at least on ROB's up air, is for the knockback to be more vertical the more hitboxes of the multi-hit attack connect. But it also could just depend on which hitbox the move finishes with or any number of other things; I really don't know. What's the answer on this one?

 

[DrinkingFood]

Dsmash launching hitbox (last hit) sends at 70° away from ROB.
Up air 1st and 3rd hits send at 45° away from ROB, and the 2nd hit sends 50° away from ROB. Depends on which hits last of the 3.
"Away from ROB" means whatever direction their character's center is from ROB's center as the move hits (left or right).
DI can change these angles by up to 18° but other than that the angles don't change.