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, and correlated home run apex with wall height and distance.

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: Mark Trumbo, 4/29, 6.83 HRD, 225 HRP

Most Towering Home Run in 2013: J.P. Arencibia, April 4th, 145 feet, -0.67 HRD

Most Line Drive Home Run in 2013: Edwin Encarnacion, April 4th, 46 feet, 0.49 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:

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

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