If you are watching the ball position AS THE DEFENSE MAKES A CATCH,
you need to be on the line. Stand tall and look over the players as you can. Tell the coach to get the heck out of the road... or any other expletive you can think of quickly. Do as Mike said and talk to the runners/players if there is time.
If you are watching the ball HIT THE GROUND because there is not going to be a defensive catch, the baseline is still the best place to be. However, if you need to,
take a couple steps off the line (into fair or foul territory) and watch where the ball hits the ground. Again, Tell the coach to get the heck out of the road... or any other expletive you can think of quickly.
"Are you going to make the call for us coach? How about you F3? THEN GET OUT OF THE WAY!"