its all about reading your opponents face and body position, and acting off the instinctivly... just spar... pain is a good teacher, no one can react outside of flinching/putting their hands up to just watching the glove leave the chin... it's too quick... all you'll get off is a parry or a block...

To efficiently duck, roll and slip you need to understand timing and where your opponetents weight is and what his range is.

Just spar and it becomes instinct.

SPAR!