Home Run Damage

If you follow me on Twitter, you probably hear me talking about this “Home Run Damage” statistic. I get a lot of questions about it, so here is my place to answer them.

Greg Rybarczyk created HitTrackerOnline.com, now ESPN Home Run Tracker, a great website that tracks every home run hit since 2006. It shows how far a home run actually went, replacing myth with objectivity. I had the idea over at The Platoon Advantage to use this objectivity to find the most awe-inspiring home runs in 2011, which is where the Damage statistic originated. I also tested the Just Enough theory, mapped out to which angle more home runs are hit in each park, correlated home run apex with wall height and distance, and created home run similarity scores.

Basically, home run damage compares the speed and distance of a home run to the average for all home runs, using z-scores. Only 14% of all home runs have a Damage above 2. Fewer than 2% have a Damage above 4. The truly elite home runs (24 out of the over 34,000 hit) are above 6. The reverse is true for negative Damage. Home runs with negative damage are simply below average.

I have now switched to using the Standard Distance of a home run instead of the True Distance. True distance measures how far a home run would have traveled if it was allowed to fall completely back to earth and not into the stands. Standard Distance takes the True Distance and factors in altitude, temperature and wind. This standardizes all home runs to the environment and makes for a much better comparison, even if it may oppose what our eyes see.

Most home runs get a double portion from distance and speed. In general, long home runs come off the bat faster than short home runs. The correlation coefficient between True Distance and Speed Off Bat is 0.46. On most days, the longest home run hit will be the most damaging as well, but that is not always the case.

I have also created another stat called Home Run Perception, which attempts to quantify which home runs are perceived as being longer than they really are based on how far past the wall they would have landed and what their apex was. Follow that link to learn more about it.

Win Probability Added  is not a part of this calculation. I know the “Damage” moniker implies a bit of that, but I don’t have WPA data for every home run, so this is not possible.

Anyway, the fun stuff. Here is the most damaging home run in my data set. Adam Dunn versus Glendon Rusch, September 27, 2008. This swing resulted in an incredible 7.92 points of damage. It is over four standard deviations above average in distance and over 3.5 in speed:

And what about the least damaging home run? Take it away, Jason Bay and your -8.09 points of damage:

Most Damaging Home Run in 2013: Mark Trumbo, 4/29, 6.83 HRD

Highest Perception Home Run in 2013: Roger Bernadina, May 29th, 230 HRP, 2.38 HRD

Most Towering Home Run in 2013: David Ortiz, May 30th, 151 feet, -1.66 HRD

Most Line Drive Home Run in 2013: Jason Kipnis, May 26th, 41 feet, -3.39 HRD

Fastest Home Run in 2013: Mark Trumbo, 4/29, 120.1 mph, 6.83 HRD

And finally, here is a list of all home runs in 2013 and their damage:

Here are the top 100 home runs since 2006:

If you have any more questions, contact me on twitter @stealofhome and I’ll be pleased to answer them.


11 Comments on “Home Run Damage”

  1. […] Now that there is a base of understanding, it’s time to play around with HRP. I also mention home run damage (home run distance plus speed off bat). If you are unfamiliar with the concept, check out my basic […]

  2. Anonymous says:

    Love this site.

    Would it be possible for you to list the top five or ten most damaging homeruns of 2012? I can’t seem to find that information on the site. I also can’t find your list of the historically most damaging taters.

    Keep up the good work.

  3. […] For an introduction to Home Run Damage along with a list of all 2013 home runs, read this page. […]

  4. […] With regard to his methodology, St. John writes: […]

  5. Eric says:

    Do you feel it is merely coincidence that (a) 0 of the 100 most damaging HRs since 2006 and (b) only 1 of the ~200 most damaging HRs of 2013 occurred at Camden Yards?

    Even if we assumed all stadiums were created equal in terms of hosting high-damage HRs — which I think probably isn’t true, given the Orioles’ relatively consistent employment of both sluggers and terrible pitchers — it seems pretty unlikely that one park would be so underrepresented both in 2013 AND over the course of the past 7 years.

    I’ve long believed that there’s something wrong with the batted ball data coming from Camden Yards, particularly with regard to fly balls (and even more particularly with fly balls hit to CF and RF). Initially, the only real evidence I had for that belief were laughably extreme home/road UZR splits for players like Adam Jones and Nick Markakis. But given that these HR damage numbers also seem to indicate Camden Yards is a rather remarkable outlier, I’m wondering if this could be related to the same issue that might be skewing the UZR numbers. Would be interested to know what you think on the issue.

    • That is an interesting thought, though I’m not certain these numbers come from the same data as uzr. That would be a question for greg. Among parks with at least 500 HRs, oriole park has the 3rd lowest maximum hrd home run behind yankee stadium and progressive field. Perhaps there is a humidity measurement missing? Not sure.


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