[tmagan]

Consider this hypothetical NFL situation:

Team A has the ball at their own ten yard line with 2:35 left in the game up two points. Team B has no timeouts. The next play the running back is tackled in between the hash mark beyond the line to gain for a first down at their own fifteen yard line. Normally, Team A will let the clock run to the two minute warning and then take three knees to end the game. However knowing this right after the running back is tackled, a member of Team B hits the running back late for a fifteen yard unnecessary roughness penalty. It is fifteen yards, but in the NFL, the clock in that situation will not start until the next snap from scrimmage. Therefore Team A has to run a play before the two minute warning. If they do not get a first down after running two plays post the two minute warning, Team A would have to punt the ball away with 40 seconds left to Team B with a decent chance to get into field goal position to win the game.