of elite rushers. Wish I could remember who or where it was, but unfortunately I can't. Anyway, my recollection is that it talked abouta good edge rusher being explosive at the snap, and the ability to be quick with change of direction. I believe also an ability to retain speed and balance while getting small, meaning getting around the edge, quickly and on balance while giving the blocker a smaller target to block.
This is an interesting video on pass rush skills:
https://www.youtube.com/watch?v=TGYEZ67cHe4&list=PL59FC7ADFC1DC0716&index=3