Yes. Coming off the hand, it looks like it's coming straight for your head. The initial reaction is to back off the plate. By the time you realize it's dropping right over the plate, you can only lunge at the ball. Thus the "knee-buckling" curve ball. Now, most hitters who actually make it to the big leagues can pick up that it's going to be a curve from the delivery and release point and adjust. The traditional up and down curve ball is a slow pitch by big league standards and had a looping curve. Kerry's delivery on his curve was well-disguised, was a relatively fast pitch, and had a real tight, whip-like break. I smile everytime a hitter backs away from a Marmol slider, only for it to break right over the plate for strike 3.