It seems like every year since we’ve had the ability to measure exactly how the baseball is spinning, flying, and landing, we’ve had revelations about how different the ball is. That isn’t to say that things weren’t a little different this year — because this year, baseball told us they changed something about the ball. They had deadened the ball, an internal memo stated, by changing the construct slightly. Balls should lose a foot or two from 2020 fly balls that would’ve gone 375 feet, and an analyst suggested that might cut homer rates by around five percent.
Did it? Through this past weekend, we have over six thousand balls that have been put in play, so to some extent we should be able to answer this question. But, as you drill down into the various ways the ball is behaving differently this year, there might actually be a surprising takeaway waiting at the end.
First, it looks like batted ball distance is down, if you control for exit velocity (95-100 mph included) and launch angle (20-25 degrees included).
Distance is down! Worst of the Statcast era! Write the big headline! But wait, it’s still cold April in a lot of places; just look at that April column to see that distances are usually down early in the season. If we use the same April adjustment we saw in 2018, these batted balls should finish with about a 348-foot distance. So distance is down, but not by much, and maybe in the range that baseball predicted we’d see.
Here’s something strange, though. If you look at home run rates, 2021 is seeing the second-highest April home run per nine inning rate in the Statcast era. If distance is down, why are homers steady or even up? Check out home runs per fly ball, which look like they’re down until you scan across and look at April home runs per fly ball.