May 22, 2017
Detroit's Earthworm Preservation Society
Balls hit in the air are one of the big stories of the 2017 season. A record number of them are going over the fence, but the larger narrative has been about how players are seeking to hit more balls in the air—elevate is the term of choice—with improved results. Ryan Zimmerman—nearly stick-a-fork-in-him done last year, MVP contender this year—is the poster child, but greater launch angles have been a theme throughout the game.
Rob Arthur of FiveThirtyEight has pointed out that this hasn’t necessarily benefited hitters, but it is, if nothing else, a thing. How big a thing? Well, through games of Saturday (all 2017 statistics in this article are through Saturday), 45.7 percent of batted balls have been hit on the ground this year, compared to 46.1 percent in 2016, which in turn was lower than 2015’s 47.0 percent. So far this year, batters are hitting ground balls at the lowest rate since 2011.
Now, it’s easy to understand why batters might want to avoid grounders. Per Baseball-Reference, batters are hitting .243 with a .265 slugging percentage on grounders. In contrast, they’re hitting .205 with a .642 slugging percentage on fly balls. That .642 slugging percentage is fueled largely by homers—fly balls are yielding an .087 batting average and .145 slugging percentage on non-homers—but that’s a little like saying wine tastes bland without grapes. More elevation yields more dingers.
This isn’t to say that a player can’t have a successful career hitting a lot of ground balls. Or that some batters might not be more successful if they hit more balls on the ground. But the trend is clear: Batters are hitting more balls in the air.
Pitchers, though, are trying to prevent that. On our player cards and in the BP Annual, we list pitcher ground-ball percentages, not fly-ball or line-drive percentages. And for good reason: So far this year, pitchers in the top 10 percent of ground-ball percentage have a combined 3.66 ERA. Those in the bottom 10 percent are at 5.07. As I pointed out last summer, pitchers who get a lot of ground balls are, generally speaking (there are always exceptions, like the fly ball-generating Max Scherzer), more successful than those pitchers who don’t.
So there are two opposing trends in 2017: Pitchers want batters to hit on the ground, and batters want to hit pitches in the air. Who’s winning?