Sacrifice Fly
A fly ball deep enough to score a man from third, and one of the odder corners of the scoring rules.
What it actually is. A sacrifice fly is a fly ball or line drive caught for an out on which a runner tags up and scores. The batter is not charged with an at bat, so his batting average is untouched, but he is credited with an RBI. It only counts if a run actually scores: the same ball that moves a man from second to third is just a fly out.
What somebody who knows the game gets out of it. The sacrifice fly is worth having as a concept because it is one of the few situations where a specific batted ball shape is the goal. With a man on third and fewer than two out, a medium fly ball to the outfield is worth more than a hard ground ball, and hitters do measurably change their approach there. It is also the clearest case of the rulebook rewarding an outcome the hitter only partly controls, which is why it is excluded from at bats but not from on base percentage.
The numbers worth knowing. A team hits something like 35 to 45 sacrifice flies a season. The single season record is 19 by one player.
What people get wrong about it. A sacrifice fly does not help batting average but it does lower on base percentage, because it stays in the OBP denominator. A sacrifice bunt is excluded from both. There is no consistent logic to that difference, it is simply the way the rules were written at different times.
At Little League and travel ball. Tagging up is one of the most reliably missed plays in youth baseball, and it is free runs. A 10U team that teaches its runners to tag on every catchable fly ball with fewer than two out will score several runs a weekend that its opponents do not, and the drill takes ten minutes.
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