Either a right fist out or red flag
The rule book takes a full page attempting to explain what to do in all possible situations when any runner leaves early before a hit. I will try to simplify it. It's not easy though. There is one loophole in the rule that allows the offense to go unpenalized. If a runner or runners are forced to advance and have left early and the batter gets a "clean" hit. No penalty is imposed. A "clean" hit means it was a single, double or triple in the umpire's judgment. If it was a hit and an error or an advance on the throw, the batter will be sent back to the base that was the scored value and all runners must go back to the bases they originally held or the one nearest the batter. Any time a base becomes available after a hit, runners will be sent back. Here are some basic keys that help simplify the rule:
1. If one runner is guilty they are all guilty.
2. You move the batter-runner back to where you judge the value of the clean hit. Any advance made by him, beyond his scored hit, is nullified.
3. Place all runners back on their original bases whenever possible. Put them as close as possible to the batter-runner after placing the batter-runner at the base judged to be the clean hit.
4. If any bases become empty due to any runner or the batter-runner being put out, return the runners to those bases.
EXAMPLE: Bases loaded, no outs. Batter hits a "clean" double, and tries for third thinking the throw is going home. The throw is cut-off and they get him out at third. Before the hit a runner left early. Guess what? The batter is out and ALL runners return. Because his out left bases empty, you put all runners back to their original bases. The offense just loves that call!
In that same play, if the out on the batter had been the third out, no runs would count due to the fact that they could have been put back if it had not been the third out. The really love that call!!!
When a runner leaves early he remains guilty even if he returns before or after a hit.
EXAMPLE: A runner on 2nd leaves early, then a fly ball is hit to right field. The runner retouches after the catch and heads for 3rd. The throw gets past F5 and the runner scores. RULING: You put the runner back on second.