Why Study Foul Balls?: Let the Lessons Begin

Copyright (c) FoulBallz
Copyright (c) FoulBallz

Why study foul balls?

Foul balls are the most under-appreciated and under-studied aspect of baseball. They are the evil step-children of the game. They are demonized. Yet they are coveted and much sought after by fans of the game. Go to Instagram, Twitter, Facebook and other social media sites and you’ll see thousands of happy fans celebrating their snags. Yet, for as much joy they bring to fans, they are maligned by baseball organizations all over the globe. But why?

It doesn’t make sense for baseball to not study foul balls. By rough estimate, there are roughly 30 hit or tossed into the stands on average per game. Our most recent data indicates there are about 46 total foul balls on average per game. That’s more than any other batted ball. And they count as part of the game. They count as a strike. Twice. They are counted for outs when caught. Runners can tag up and advance, including scoring, on a foul ball. So it’s not like they aren’t a crucial aspect of the game. But they remain ignored.

They are both loved and loathed. They are often listed as the reason for fan injuries by fans who are hit or who hurt themselves as they go for a foul ball.

Yet, after 100 years of foul balls, no one studies them. FoulBallz.com is the first and only site to do so.


The value of foul balls in is simple:

According to our database that draws upon Retrosheet.org data from the last century of baseball, Derek Jeter faced off against Felix Hernandez 53 times between 2004 and 2012. Of those 53 meetings, Jeter never fouled off more than five (5) fouls in one at-bat, and he did that only once. The other at-bats had 0-2 foul balls slapped.

Of the at-bats with foul balls, Jeter was able to get on base five times in 18 at-bats. Of those five, Jeter drew a base-on-balls three times. The other two were a single and a double.


What does something like this tell us? It tells us Jeter should have waited for his pitch more often with Hernandez. When he swung at a pitch that ended up being a foul, Jeter stood only a 27.8% chance of reaching base afterwards. So for this matchup he should have swung only when he was positive he could put it in play or draw a ball; in other words, he shouldn’t have swung at anything “close,” but instead waited for the pitch in his sweet spot.


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On the other hand, Jeter faced off 27 times against Clay Buchholz during the same timeframe. Whereas Jeter fouled off a total of 26 balls against Hernandez in 53 meetings at the plate, he had at least one foul 12 times against Buchholz for a total of 22 in 27 at-bats. This translates into Jeter slapping more fouls per bat (about 1.83) against Buchholz than he did against Hernandez (1.44).

Of those 12 at-bats with one or more fouls, Jeter got on about 42% of the time (a much better rate than against Hernandez). This time on two errors, two walks and one single. Only once did he strike out after brushing away at least one pitch.

What’s this say to us about what Jeter’s approach should have been facing off against Buchholz? Swing away. He could foul off more pitches against Buchholz and do two things: Drive up Buchholz’s pitch count and remain close to having a 50/50 shot at getting on base.

It’s data like this that’s missing from the record, and the data we will be bringing you now.


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Progressive Field. Foul Territory

Our database is completed and I’m working on bringing you the over 50 years of foul ball data, as complete as the historical records allow. Once done, we can even study how weather may play a role in the number of foul balls or whether day games have more fouls than night games. All this data is crucial to helping players better understand how they bat and how they can straight out their hits. A foul ball toward 3B for a right handed batter tells us he was out ahead of the ball, and he can make that adjustment at the plate, but if a player fouls off more pitches against one pitcher in particular, it means that pitcher is fooling the player on a regular basis, getting him to chance bad pitches. By analyzing the number of fouls a batter hits against a certain pitcher, we can see there is a deep, non-explored wealth of information about batter-pitcher match-ups.