Should Siri call the strike zone?

Even though the Reds are struggling this year, it’s an exiting time to be a baseball fan: teams are using new defensive formations around the diamond, new hitting strategies are emerging, and some teams are learning that people see what you do while browsing the internets!

The “big picture” trends in baseball are well known: pitchers are throwing harder than ever before, hitters are becoming an endangered species, and teams are placing players in strange new configurations. The result of these trends is also well known: baseball is feeling a bit “run down”.

It is rumored that MLB is considering a few options to correct for the decline in offense, including lowering the mound (something that has not happened since 1968). The early evidence, however, indicated that MLB has nudged umpires to call a slightly smaller strike zone than they had in previous years. Grantland reported that the strike zone, which had previously expanded every year since 2009, was now starting to recede around the edges. An article from John Roegele (Fangraphs) argues that the strike zone has gone from 475 square inches in 2014 to 457 inches in April of 2015.

I don’t have the aggregate strike zone data, but we can take a look at the “bottom line” trends in MLB to see if there has been a corresponding increase in offensive statistics across the league. Here are the projected 2015 “counting stats”:

The Counting Stats

Compared to the recent past, home runs, runs scored, and stolen bases are all up. Baseball, it seems, has rolled back the offensive clock by half a decade in one offseason. So what is behind this rise in offense?

The Rate Stats

The rise in strikeouts over the past ten years has been one of the most discussed aspects of MLB’s power outage. For the first time since 2004, however, the strikeout rate is falling, down by 0.3% from 2014. While the league’s on base percentage (and walk percentage) has not budged from 2014, slugging is up almost ten points.

One argument for why offense is declining is that pitchers are throwing harder than ever before. This is easy to verify: since 2009, the average fastball velocity has been on the rise:

Up until this year, the rise in fastball velocity has linked to better training techniques, coaches putting young pitchers on a pitch count, and reliever specialization. In 2015, however, we see average fastball velocity declining. Now this decline in fastball velocity could be due to a variety of factors including injuries or the weather.

Im going to wander into dangerous territory and speculate that fastball velocity is partially driven by strike zone size. Under this idea, the larger the strike zone, the easier it is for pitchers to record a strike. Since pitchers feel it is easier to throw strikes, they can go for bigger pitches than before since there is a smaller risk they will end up walking the batter. With a shrinking strike zone, hitters have to defend against a smaller area and are facing slower pitches than before, making it easier to drive the ball (hence, the increase in slugging).

I don’t want to overstate this claim because there still needs a lot more evidence on the relationship between fastball velocity and strike zone size (for one, it could be that at the end of the season fastball velocity rises above its 2014 levels). Yet if small, almost unnoticeable changes in the strike zone can have large impacts on aggregate scoring, it might be time to start letting computers call balls and strikes.

There is a tipping point in any sport where “the human element” goes from being “part of the game” to a distraction and source of frustration for fans. ESPN now lets fans see every strike call that goes agains their team. Furthermore, it has to be frustrating for both pitchers and hitters to learn and re-learn the strike zone every year.

What do you think, Nation? Should we start letting Siri call balls and strikes?