Make a line drive go through. On fly balls, if it's obviously going to be caught - go back to second to tag up. Obviously, the coach doesn't have time to go over all of possible scenarios in a game. Then, if there is a passed ball or a wild pitch, the runner is in position to score. Tagging up on fly balls Make the line drive go through.
Timing is very important.
If you leave the base too soon, they can appeal the play and you can be called out. If you leave the base too late, they may throw you out at the plate. If it's going to be a close play, the runner must leave the base at the exact time the ball touches the glove of the outfielder. The runner must be able to observe the catch himself, rather than relying on the third base coach to tell him to tag up. The only way the runner can clearly see the ball while tagging up at a base is to have the foot on the base that will allow him full sight of the baseball as it is touched by the outfielder.