Officials, especially the line judge and head linesman, always work to get the forward progress spot. In order to do so, they are taught to trail the play by a few yards and then square up once the ball is dead. But, when a big progress spot is important, the NFL prefers officials to get ahead of the action and wait for the ball to arrive.
Line to gain. When it is under five yards to go for a first down, and it is third or fourth down, watch the wing officials at the snap. Instead of trailing the play, they immediately advance to the first down marker. If the ball makes or crosses the line to gain, they know and have an exact spot. If the ball never reaches the line to gain, the two officials work backwards to get the spot.
Here is the philosophy behind this mechanic: If the line to gain is the 23-yard line, it is vital for the officials to be at the 23 and have a good look down the line. If the ball is short of the 23, the NFL doesn’t care if the officials mark the ball at the 22½-yard line, or the 22⅞-yard line. But, if the officials miss the ball getting to the 23-yard line, it is a big deal and a big miss.
Big calls at the goal line. Similar to the line-to-gain, when the ball in inside the five-yard-line, the head linesman and the line judge will break to the goal-line at the snap and work backwards. Again, if the ball is spotted at the half-yard line or the quarter-yard line, the NFL doesn’t care. The NFL, teams and fans do care about the goal line.
Conversely, when the offense is pinned up against their own goal-line, the officials are on alert and use different mechanics. If the ball is on the three-yard line, the wing officials will retreat to the goal line at the snap to make sure the entire ball gets out of the end zone and then mark progress in the field of play. Again, what’s more important: a safety or spotting the ball within half a football length between the four and five-yard line? A great example of this mechanic happened this weekend when the San Francisco 49ers failed to get the ball out of the end zone and gave up a safety (video).
Short wing officials are experts in adjusting to get the proper forward progress spot and amateur officials can learn much from watching them.