Tagging Up in Baseball, Explained
What it means, when a runner can leave the base, and how the sacrifice fly works.
In one sentence: on a caught fly ball, a runner must stay on their base until the fielder first touches the ball, and then they can advance at their own risk.
How Tagging Up Works
When a fly ball is hit, runners have a choice. They can lead off in case it drops, but if it is caught they must return and touch their base before advancing. The key timing point is the moment the fielder first touches the ball, not when the catch is secured. A runner who is on the base at that instant may take off immediately.
That is why a runner on third can score on a deep fly to the outfield: by the time the outfielder catches and throws, a fast runner who tagged at the catch is already most of the way home.
Leaving Early and the Appeal Play
If a runner leaves before the fielder touches the ball, they have left early. The defense can appeal by throwing to the base the runner left before the next pitch. If the umpire agrees, the runner is out, even if they reached the next base safely. This is why coaches drill runners to wait for the catch on medium-depth fly balls.
When to Tag and When to Hold
- Deep fly, fewer than two outs: tag and advance, especially from third.
- Shallow fly: usually hold, because the outfielder's throw will beat you.
- Two outs: do not tag; run on contact, since the inning ends if the ball is caught.
- Ground ball: no tagging up; advance as usual.
Tagging Up FAQ
What does tagging up mean in baseball?
Tagging up is when a base runner waits on their base until a fly ball is caught, then advances to the next base at their own risk. The runner must be touching their base at the moment the fielder first touches the ball.
When can a runner leave the base on a fly ball?
The runner can leave as soon as the fielder first touches the ball, not when the catch is completed. Leaving the instant of first contact is what lets fast runners score from third on a deep fly.
What happens if a runner leaves too early?
If the runner leaves before the fielder touches the ball, the defense can appeal by throwing to the base the runner left. If the umpire agrees the runner left early, the runner is out.
What is a sacrifice fly?
A sacrifice fly is when a batter hits a fly ball deep enough for a runner to tag up and score after the catch. The batter is out, but the run counts and the batter is not charged with an at-bat.
Do you have to tag up on a ground ball?
No. Tagging up only applies to caught fly balls and line drives. On a ground ball there is no catch in the air, so runners advance normally, and forced runners must advance.
Teach your runners to read fly balls and learn the defensive side in the runner-on-third defensive guide.
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