[Rich]

Originally Posted by Robert Goodman

Since I can't see the video, I have to ask whether the player who blocked the kick appeared to propel himself into the air off the snapper's back (using the contact to gain or maintain altitude), or stepped on his back in an effort to get past him. The first would fit case (b) above, but the second would not be any of those cases. In other words, was the snapper's presence an advantage to the defender, or would he have been just as well (or better) off to have been able to plant that foot on the ground?

Robert

I see it the second way. He came off the back and never used the step to gain an advantage other than a quick way through the line play.