Why do fielders try to catch infield flies?

With runners on first and second in the seventh inning of the Mets’ 5-2 win over the Braves on Friday night, Jose Reyes hit a pop-up to the left side of the infield. The infield fly rule was correctly invoked, meaning Reyes was automatically out. As the ball began its descent, there was a little miscommunication between Atlanta shortstop Omar Infante and third baseman Chipper Jones. Jones cut Infante off in trying to make the catch at the last second, and the ball bounced off the heel of his glove and back toward home plate. The runners both moved up. Braves catcher Brian McCann got confused and threw to first, apparently to get Reyes out a second time. While Eric Hinske applied a tag to the already-out Reyes and looked bewilderedly at the first base umpire, Angel Pagan broke for home and scored.

I don’t think any play can better introduce a question I’ve long had about baseball: When the infield fly is called, why do infielders try to catch the ball anyway?

The infield fly is one of those sports rules everyone kind of knows without exactly knowing—like Illegal Procedure in football and Illegal Defense in basketball. Established to protect baserunners, the infield fly is invoked on an infield pop-up when there are runners on first and second or the bases are loaded and there are fewer than two outs. The rule is in place to prevent an infielder from purposely dropping the ball and turning a double play on the runners, who have to stay close to their own base while the ball is in the air. When the infield fly is called, the hitter is automatically out, and the baserunners advance at their own peril.

The rule makes perfect sense to me; it was wise of baseball to close that loophole. But I’ve never understood why infielders always go through the trouble of actually making the catch. Sure, it’s a pop-up, and pop-ups aren’t terribly difficult to catch. On the other hand, pop-ups don’t go anywhere when they hit the ground. Trying to catch a pop-up opens up the possibility that the ball will, as it did on Friday night, bounce far away from the infielder, thus allowing the baserunners to move up. A pop-up that isn’t caught, though, will not stray from its expected landing spot. It will hit the ground and have a small dead cat bounce. There is virtually no chance that it will get away from the infielder closest to it. There is virtually no chance the runners can move up.* In fact, there is a much better chance that, seeing the ball hit the ground, the runners will get confused, think they have to advance, and run into an extra out or two.

*The three ways a ball could bounce away if infielders let it drop seem to me extremely unlikely: 1. That the ball hits an unaware infielder; 2. That it hits a base; 3. That it hits where the grass meets the dirt. The third is the most likely of these, and even then, the ball’s trajectory is so downward that, according to physics, I’m pretty sure it wouldn’t bounce that far away. It doesn’t have enough horizontal force (like a hard ground ball) to take a large bad hop into the outfield.

I understand that what happened to the Braves on Friday night was a freak occurrence—one of those “you can see something you’ve never seen” moments on which baseball prides itself. But letting infield flies drop to the ground prevents those freak occurrences. Plus, infielders wouldn’t have to experience the once-every-few-years embarrassment of dropping a pop-up.

Head up, Chipper.

10 responses to this post.

  1. Posted by John S on April 24, 2010 at 1:10 PM

    There are probably two reasons why infielders try to catch infield flies? 1) The odds of the ball bouncing away are unlikely, but the odds of something like what happened to the Braves happening are ALSO extremely unlikely, so you might as well go with your gut instinct, which is to catch the ball. 2) When you’re looking for the ball in the air, there’s always the chance that you don’t hear the ump, or you mishear the ump, or you mistake someone else’s voice for the ump’s. And nobody wants to embarrassingly let a pop up drop if it WASN’T called an infield fly, so you may as well catch it.

    Also, I guess a third option is that the players themselves don’t really understand the infield fly rule, but I would give them more credit than that.


  2. Posted by Josh on April 24, 2010 at 11:58 PM

    Yeah I agree with John on 1; I think the odds of dropping a popup might actually be lower than the odds of a weird bounce. Another thing is I think getting out of the way of a popup could actually be kind of awkward. You still want to be close to it but not too close. When you’re so attuned to getting underneath the ball, it might be difficult to get in position NOT to catch it. Not to mention psychologically, it may be difficult to force yourself not to catch the ball.

    Also, you say “there is a much better chance that, seeing the ball hit the ground, the runners will get confused, think they have to advance, and run into an extra out or two.” I think this may be true the first time but once a player or team does it once, the other team will probably catch on and there wouldn’t be much long-term advantage.


    • Posted by Tim on April 25, 2010 at 12:37 AM

      Maybe we’ve watched different games: I’ve never seen a pop-up that hit the ground untouched take a weird bounce whereas most of the dropped pop-ups I see tend to sneak away from the fielder at least a little (and most drops either hit the heel–as it did with Chipper on Friday–or bounce out of the palm).

      I don’t think the positioning would be awkward; several players stand near pop-ups without catching them now (think the 3B who “backs up” a SS). And the psychological effect of forcing yourself not to catch the ball would wear away at least as quickly as the “confusion of the runners” point you disagree with and quicker than the humiliation of a dropped pop-up.


      • Posted by Josh on April 25, 2010 at 12:28 PM

        In addition to doc’s analysis, I’d add that saying this (“I’ve never seen a pop-up that hit the ground untouched take a weird bounce whereas most of the dropped pop-ups I see tend to sneak away from the fielder at least a little”) is relying on the wrong comparison. The comparison is between the Probability (Dropped Popup AND Ball Sneaking Away GIVEN attempted to catch)* and the Probability (Odd Bounce/Mishap GIVEN attempt not to catch). I think the latter is higher and that one reason you don’t think it is is that virtually all infielders, as you say, do attempt to catch the popup so the sample size of potential weird happenings is really really low.

        *NOT Probability (Ball Sneaking Away GIVEN Dropped Pop Up) which you use.


        • Posted by Tim on April 25, 2010 at 4:09 PM

          You’re right, Josh; I haven’t seen a lot of pop-ups hit the ground unimpeded. But I HAVE seen plenty of fly balls lost in the sun hit the ground unimpeded, and despite their extra horizontal force (which propels them all the way out to the outfield and means that, almost unequivocally, they hit the ground at a more acute angle than a pop-up), even these typically don’t bounce away.

          And while I didn’t explicitly make the same comparison you did, I was aware of it, and I simply disagree with you. I think the P(Dropped Ball Bouncing Away Given Attempt to Catch) is greater than P(Ball Bouncing Away Given No Attempt to Catch).


  3. Posted by doc on April 25, 2010 at 12:14 PM

    Having played a lot of baseball, both infield and outfield, some on windy fields, it is best to catch the ball. Strange things do in fact happen when you don’t catch it – not all the time, but more than you could imagine. Check out all those blooper reels and you will see what I mean. To make an adjustment not to catch a ball is much more difficult than doing what you have been taught to do all those years. Plus, it’s not just one person here. Often there are as many as 3 (I have seen 4) infielders around a pop-up. Let’s say you decide to let it drop. How are you going to notify the other 2 or 3 guys? And what do they do when they are notified. Do they run in the other direction? Then who is responsible for the ball? Is it the guy who said let it drop. What if he bumps into someone trying to get out of the way of the ball? You get the picture. Just catch the damn thing and fuggetaboutit. As you noted Tim, the infield fly rule is to protect base runners, not fielders. Fielders protect themselves by catching the ball.


    • Posted by Tim on April 25, 2010 at 4:04 PM

      First off, doc, I don’t like the implication that I didn’t play a lot of baseball or that the diamonds of Lincroft Little League were not every bit as windy as most. Not having cable television as a youngster compelled me to watch a lot of those old blooper reels run on boring Saturday afternoons, and I can reinforce that I have NEVER seen a pop-up that was not touched during its descent take any kind of crazy bounce.

      Furthermore, I don’t get the logic of “It’s hard to not catch a ball.” It’s very easy to not catch a ball; you just don’t catch it. This isn’t missing a free throw where you have to come within a certain proximity of making it and mess with your fundamentals and miss in a very specific way. You go to the spot where you would catch the ball, and then you take two steps back and don’t interfere with the ball’s descent. I also don’t see why the infielders would have any more trouble communicating responsibility for the ball than they do in normal circumstances. The catcher should give the “DROP” order once he sees the ump has called the infield fly, and the closest infielder should take responsibility for the ball once it does drop (by, say, yelling “I got it!”). The other players should cover their respective bases.


  4. Posted by John S on April 25, 2010 at 5:01 PM

    I’m just glad that this has generated more discussion than Josh and I’s whole debate about the First Amendment.


    • Posted by Tim on April 25, 2010 at 11:40 PM

      Maybe next time, John, you should apply your contrarianism to something people really care about, like the infield fly rule.

      And besides, we both know a post isn’t a success until Jane comments on it.


  5. Posted by doc on April 26, 2010 at 10:22 AM

    Regarding the First Amendment discussion, John, if it wasn’t for this crucial Amendment, we might not be having this debate. Tim, I didn’t mean to imply that you didn’t play baseball, however I did play at a relatively high level, college, and those pop-ups go really high. The first game I ever played in college (by the way I was in the first freshman class ever allowed to play varsity, and the next year was the first class that used aluminum bats) someone hit a sky high pop-up to right field (my position) in between 2nd and right. I was doing everything in my power on a windy day just to position myself properly while the 2nd baseman was out there too. Trust me, to even think about dropping it purposely and in the proper place is not be easy. Granted, these guys are pros, but they struggle too at times. I do recall Derek Jeter letting one drop once with the infield fly. No big deal, no one advanced and no one was caught napping. But then again, everything Derek Jeter does is cool, even though I am a Mets fan. I wish I could say that about Jose Reyes.


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