A coach or infield leader will yell double cut.  Double cuts are needed when a ball is hit to the fence and there is gonna be a long throw to a base.  On a ball hit down the right field line and the expected play at 3rd base, the 2B will be the lead relay guy and 1B will be the trail man.  SS will cover 2nd base and the pitcher will be the back up at 3rd base.