Nathan: Exit speed and home runs

From SABR member Alan Nathan at The Hardball Times on July 18, 2016:

Back in March, prior to the start of the 2016 season, an article entitled “A Baseball Mystery: The Home Run Is Back, And No One Knows Why,” by Rob Arthur and Ben Lindbergh, noted that the number of home runs per batted ball during the 2015 season was significantly larger post-All Star Game than pre-All Star Game. They observed that the increase was accompanied by, and perhaps caused by, a small ~1 mph increase in the mean exit speed. The authors speculated about various reasons that might explain the increase.

Inspired by their article, I decided to do a bit of research on my own, comparing home runs and exit speeds for the months of June and August. I was particularly intrigued by how a small increase in exit speed could lead to a relatively larger 13 percent increase in home runs. I wrote a brief article, Home Runs and Exit Speed, and posted it on my website, explaining how this can happen without speculating on why there was an increase in exit speed.

Since then, the topic has remained of great interest. Home runs are always front and center, and have been so this season more than in most. Commissioner Rob Manfred even addressed the increase in home runs at his annual press briefing during All-Star week. So I decided to roll up the sleeves again and dig into some additional analysis, using the publicly available Statcast data for the 2015 and 2016 season, courtesy of Baseball Savant.

Read the full article here:

Originally published: July 18, 2016. Last Updated: July 18, 2016.