The infield fly rule is the most frequently misunderstood rule in baseball, and the people who get it wrong loudest are usually the ones who think they understand it. The rule exists for one specific reason — to prevent a defensive trick play that would otherwise be unstoppable — but the way it actually works is buried under three layers of conditions and umpire judgment that even experienced players sometimes mangle.
The most famous example came in the 2012 NL Wild Card Game between the Braves and Cardinals. Atlanta had runners on first and second with one out in the bottom of the eighth, trailing 6-3. Andrelton Simmons lifted a pop-up to shallow left field. Cardinals shortstop Pete Kozma drifted way back onto the outfield grass, lost the ball, and never made the catch. With the ball dropping, it looked like the Braves had bases loaded with one out and a chance to rally. Except the umpire had already called infield fly. Simmons was out. The Braves had runners back at first and second with two outs. They didn’t score. They went home.
Was the call correct? Even MLB officials and former umpires disagreed publicly afterward. That’s how this rule works in practice — three conditions plus a judgment call, with the judgment call being the one that produces controversy. Here’s the complete breakdown.
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What the rule actually says
From MLB Rule 2.00: an infield fly is “a fair fly ball (not including a line drive nor an attempted bunt) which can be caught by an infielder with ordinary effort, when first and second, or first, second and third bases are occupied, before two are out.”
That’s the entire rule. Three conditions: less than two outs, runners on first and second (or bases loaded), and a fair fly ball that an infielder could catch with ordinary effort. If all three are true, the umpire calls infield fly. The batter is automatically out, regardless of whether anyone actually catches the ball.
The crucial part is the third condition — “ordinary effort” — which is entirely a judgment call. There’s no specific zone or distance the rule defines. Umpires consider where the ball is, who could reach it, and how hard they’d have to work to make the play. A pop-up that lands 30 feet behind second base on the outfield grass might still qualify if the umpire decides an infielder could have camped under it.
Why the rule exists
Without the infield fly rule, infielders could turn pop-ups into easy double plays. Imagine bases loaded with one out. The batter pops up to the shortstop. All three runners stay close to their bases because they assume the catch is automatic. The shortstop deliberately lets the ball drop, picks it up, steps on second to force out the runner from first, then throws to third to force out the runner from second. Two outs from one easy pop-up. Inning over.
This isn’t a hypothetical — it’s exactly what was happening in the 1880s and 1890s before the rule was introduced. Infielders figured out the trick, and runners had no way to defend against it. They couldn’t run on a pop-up because they’d be doubled off if it was caught, and they couldn’t stay if it was dropped intentionally.
The National League adopted the infield fly rule in 1895 to make the deception worthless. Once the batter is automatically out, dropping the ball intentionally doesn’t help the defense. They’d just be giving the batter and runners a free chance to advance.
What “ordinary effort” means in practice
This is where the controversy lives. “Ordinary effort” isn’t defined in the rulebook. Umpires interpret it as a play an average professional infielder could make routinely — not a great catch, not a tough catch, just a normal one.
The Andrelton Simmons play in 2012 was the perfect controversy. The ball was deep enough that some thought a shortstop wouldn’t ordinarily camp that far back, but Kozma did, and the umpire ruled that meant ordinary effort applied. Critics argued that any pop-up requiring an infielder to drift 50+ feet onto the outfield grass shouldn’t count as ordinary effort by definition. Defenders argued that the umpire is supposed to make the call when it appears one in real time, and Kozma’s positioning made the catch look routine.
Both sides have a point. The rule was written to protect runners, not to give the defense a free out, but it also has to be called in the moment based on whether the umpire thinks the play looks ordinary. The judgment is built in.
The runner-on-first-only situation everyone gets wrong
This is the most common confusion. People remember that the infield fly rule applies “with runners on base” and assume that includes a single runner on first. It doesn’t.
The rule requires runners on first AND second (or bases loaded). With only a runner on first, there’s no force play at third. Even if the defense intentionally drops the ball, they could only force out the runner at second — replacing him with the batter at first base. That’s not a meaningful gain. They’d swap one runner for another at the same base.
If you’re watching a game and a pop-up gets called as infield fly with only a runner on first, the umpire made a mistake. It happens. The rule doesn’t apply.
What happens after the call
The umpire raises an arm and yells “Infield fly, batter’s out” while the ball is still in the air. The batter is immediately out. The ball stays alive — runners can advance at their own risk just like any other fly ball.
If the ball is caught, runners must tag up before advancing. If it’s dropped, runners aren’t forced to advance, but they can run if they want to. Force plays are removed. Defenders have to actually tag runners out, not just step on bases.
If the umpire calls “infield fly if fair” because the ball is near the foul line, and the ball lands foul untouched, it’s just a foul ball. The batter isn’t out, the count doesn’t change for outs purposes, and play resumes normally.
Levels where the rule applies
The infield fly rule is used at MLB, Minor League Baseball, NCAA, NFHS high school, and Little League Major Division (12U) and above. It’s not used in tee-ball, coach pitch, or Little League Minor Division — those younger divisions remove the rule because young infielders rarely make the deception play and adding the rule creates more confusion than it prevents.
Once kids reach Little League Majors, the rule is in effect, which means parents and players need to understand it. The most common misunderstanding at the youth level is the runner-on-first-only situation — players see a runner on base, hear “infield fly,” and think it always applies. It doesn’t. Two runners minimum, with first and second occupied.
— Drew, Legion Report