Yes, I see the confusion now. I played on Xbox, where movement is done with the stick!

BTW, it feels great once you master it!

My wording must be unclear, but I am not sure which way you misunderstand. Here's the pseudo code: if (it_is_a_hit) and (no button presses since last hit), then register a critical hit. All the rules of normal hit apply, but you are not allowed gratuitous button presses (during anymation, for example). Fill free to edit my answer to make it comprehensible.