Too Late For 11th Man To Enter Field?

[Jim S]

Originally posted by sir_eldren
The catch to the defensive side of the ball is that the player has to meet two requirements to be considered eligible: At the snap, the player must (1) be on the field, and (2) be on his team's side of the neutral zone. If he meets requirement #1, but fails to meet #2 by the snap, then we've got encroachment.
-Craig

Not encroachment under NFHS rules. This is a foul for illegal substitution, as long as he does not participate. If he does, it becomes an illegal participation foul.
BTW, encroachment means breaking the neutral zone, not being on the other side of the ball. What is the foul, if any, for a defensive player (legal player, not a sub) being in A's backfield at the snap? He was there since the end of the previus play. (I know is a theoretical situation, it's for purpose of the rule.)