What I see happening is a timing issue between the ball crossing the front edge of the plate-the runner taking off-and the catcher trying to make a play. If it appears to the batter that the catcher has a good position on the runner, they could swing at the ball at the last second disrupting the catcher's attempt. It would be a fine line between catcher obstruction and interference. I may be playing this out too slowly in my mind... but this is SLOW pitch
