[MJT]

Just because he does not make the tackle or throw a block does not mean he did not participate. If hinders an opponent or draws coverage it is also IP. If ANY team A player even went out of his way to maybe block B76, he should be considered to have participated as his actions caused a reaction (drawing coverage) by the other team. Since you cannot necessarily see all of A's actions, since he changes his direction and runs toward the receiver, I think you ding him with DP. It would have been IS if he paused, but kept going towards his sideline.

It is definitly not a dead ball IS. You should call that on the defense if they none of the 12 are trying to get off the field just before the snap, but not if someone is trying to get off the field.