In 2015, the number of home runs increased over 2014 by an amount larger than one would expect from year to year fluctuations.
In 2016, MLB experienced a similar increase
In 2017, the number of home runs increased again. Many fans believed that the increase was due to a deliberate alteration of the MLB ball. MLB denied such claims and commissioned a study to determine why the home run totals were increasing.
Many of the results of this study can be found on Alan Nathan’s site. In a nut shell, the study concluded that the average drag on baseballs in those three years decreased. Interestingly, at this point, no one knows why. I am to find out with the help of Lloyd Smith from WSU and Alan, both who were part of the MLB study.
Lloyd has collected balls with high drag and others with low drag, which are visibly identical. We will make detailed measurements of the boundary layer of these balls in an attempt to find out what makes them different.
We hope to start new measurements in May 2019.