Library Update: HR/FB

The analytically minded baseball fan knows all about BABIP. BABIP is essentially a sabermetric disclaimer. It’s something we cite every time we observe something new or different in a player’s game. “It seems like Player X is getting better (or worse), but it might just be BABIP noise.” In a way, HR/FB is a lot like that, especially for pitchers.

Pitchers can dramatically improve their run prevention with a little good fortune in the HR/FB department, even if they’re not really doing much differently. To that end, we’ve updated our HR/FB Library entry to help you better understand how to use the statistic to evaluate pitchers and their runs of good and bad performance.

As always, feel free to ask questions in the comments below or to find me on Twitter @NeilWeinberg44 if you have other inquiries.

We hoped you liked reading Library Update: HR/FB by Neil Weinberg!

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Neil Weinberg is the Site Educator at FanGraphs and can be found writing enthusiastically about the Detroit Tigers at New English D. Follow and interact with him on Twitter @NeilWeinberg44.

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Brian Cartwright
Guest
Brian Cartwright

HR/FB has the wrong denominator, as 15% of HRs are LDs, not FBs, and LD definitions are kind of fluid and arbitrary.

better is to use HR/(LD(OF)+FB), flies plus outfield line drives, collectively called “balls in the air to the outfield.”

With this denominator, there is a significant difference between pitchers in their HR%

Grant
Guest
Grant

If you givery up lots of low launch angle line drives, you’re probably not going to see many of those leave the park. On the other hand, you’re probably screwed in BABIP column.

Grant
Guest
Grant

*give

Brian Cartwright
Guest
Brian Cartwright

You are correct, low angle flies will be more likely to fall for hits but less likely to go over the fence.

These can be predicted fairly well by looking at a pitcher’s groundball and popup rates. This is the only part of babip that a pitcher can reliably control – pitching in and out, up and down control the distribution horizontal and vertical angle of balls in the air to the outfield. Pitchers have very little control over anything on the ground.

One of the reasons BABIP is noisy is because it’s a combination of several stats, some that pitchers can control, and some they can’t.