Red team is defending an attack by blue team. A red player is clearly in an offside position in the center of the field about 10 yds inside the Blue team’s half, but not interfering in play. Suddenly the ball is cleared to the wing and the red team is now attacking. The ball is played to the offending red player who is now in an onside position on the edge of the PA. It is determined that the red player managed to get the ball as efficient as he did because of his original position and the speed at which the ball found him. Assuming the correct call is offside, where is the ball placed, at the edge of the PA or back up near the halfway line where he was offside? If at the edge of the PA, it seems although the red team is penalized, they have still gained an advantage because the ball is starting so much closer to the goal.
USSF answer (December 1, 2008):
The matter at the crux of the decision for or against offside is this: Where was the player at the moment the ball was last played by one of his teammates? It makes absolutely no difference where the player was before that moment.
Because the red player was in an onside position when the ball was played by one of his teammates and he than became actively involved in the play, a decision for offside would be incorrect and thus there is no reason for a restart. However, if the referee had stopped play and it is then found that the player was not offside, the restart would be a dropped ball at the place where the ball was when play was stopped.
This reasoning is reinforced by the fact that the player was in an offside position in the center of the field and not involved in play when the ball was played to the wing. It is perfectly legal to be in an offside position at any moment while the ball is in play and even at most restarts. What matters is the player’s subsequent involvement (or lack thereof) in play.