Trackman radar currently measures around 88 to 90% of all batted balls. I wrote a piece for The Hardball Times outlining this issue which you can read here. In the spreadsheet below you can find the appendix for that Hardball Times piece, including which batted balls you may wish to exclude from your own calculations.
I have written in the past about how certain batted ball types are more stable than another from one year to the next. For ease of use I will include the year to year correlations in a table below.
|Year to Year Correlations|
As you can see, Dribble balls are very consistent from one year to another. Pop ups are pretty solid, as are flyballs. The Groundball, Line Drive, and High Drive groups are not nearly as stable. Realistically, all three of these groups are very fungible, and batters may slide between each group pretty fluidly.
The purpose of these categories is not to predict what a batter may do in the future, but rather to describe what he has done in the past. If a batter is very successful due to a large number of High Drives, you should be very suspicious. You should generally expect to see random noise out of these three battle ball types, and analyze player changes over time from that perspective.
Below I have an attached spreadsheet showing the changes each player displayed between 2016 and 2017. Keep the above year to year correlations in mind when sifting through this data.
Sometime in late 2015 the baseballs used by Major League Baseball appear to have changed. How they may have changed and whether it was intentional are hotly contested topics. Regardless of how you feel on the topic, the baseball appears to be traveling five to six feet further now than it did prior to this change.
This flight can be converted to a change in effective velocity, since the ball travels around five additional feet for each additional mile per hour. Meaning the ball has an effective velocity about 1 to 1.2 miles per hour faster than what is registered. Meaning, in order for a ball from the first half of 2015 to fly as far as a ball hit in 2016 or 2017, it would need to have been hit about one mile per hour faster.
You can reverse this logic and say that subtracting a mile per hour from a ball hit in 2016 or 2017 would roughly approximate where it would have landed when using the older baseball. I have run Back in October, after the season had concluded, I ran xStats on a dataset which did just this: it subtracted a mile per hour from the balls hit in 2016 and 2017 and calculated their success rates. You can see the results in the attached spreadsheet.