This is Sung Min Kim’s third piece as part of his February residency at FanGraphs. (He gets a couple extra days because of the month’s brevity.) Sung Min is a staff writer for River Avenue Blues, the biggest independent New York Yankees blog on the web, and has freelanced for various publications including Deadspin, Sporting News, VICE Sports, the Washington Post, and more. He can also be found on Twitter. He’ll be contributing regularly here this month. Read the work of all our residents here.
Pace of play has, without a doubt, become a hot-potato subject in MLB and for commissioner Rob Manfred. The league, of course, recently made some rule changes in order to quicken game flow, alterations that mostly concern things like mound visits, commercial breaks, instant replay, and the timing of pitching changes. We even had a league executive make some, uh, interesting propositions about the ninth inning.
While many of MLB’s proposals this offseason have focused on improving pace of play, other possible rule changes have sought to more explicitly shorten games. One such idea is to increase the size of the strike zone. The idea here is straightforward: more strikes means quicker at-bats, and quicker at-bats means quicker games.
With the new pace-of-play measures already announced, we won’t be seeing a bigger strike zone yet. However, another league already put that measure in practice in 2017. Last year, before the season’s start, the KBO (Korean Baseball Organization) announced that they were going to adopt a wider strike zone.
The KBO made the decision for different reasons than MLB would. First, it seemed like a knee-jerk reaction to Team Korea’s poor showing in the 2017 World Baseball Classic. South Korea, the host of Group A in the first round of the tournament, was eliminated after the first two games, losing to Israel and the Kingdom of Netherlands (though they did beat Taiwan in their third and final contest). That early exit served as a wake-up call, inspiring league officials to think critically about the game.
But there was another reason for the change. KBO has been a high-offense environment for the past few seasons. From 2014 to 2016, the league enjoyed an average OPS of .807, .787, and .801 respectively. It was not always this way, though. As recently as 2012, KBO skewed more pitcher-friendly, believe it or not. That season, the league had a .698 OPS. Since then, hitter OPS has increased by about 100 points in just seasons, which is significant.
I could write a whole article on why that is. But for now, we’ll stick to the strike zone. After the offensive environment of the last few years, officials felt that the balance needed to shift back towards pitching after three consecutive years of inflated run-scoring. By increasing the strike-zone width and calling more strikes, pitchers would gain some advantage.
When announcing the change, the head KBO umpire official Kim Poong-Gi explained that the league would not explicitly re-define the strike zone. Rather, the intent was to maximize the size within the regulated measure. That meant, hypothetically, the pitch that touches any portion of zone boundary would be considered a strike.
And the new zone did inspire change.
Two pitches don’t conclusively prove the point, but as examples, here is Kim Gyeong-Un of the Hanwha Eagles, taking a pitch for a ball on May 18, 2016.
And here is Min Byung-Hun of the Doosan Bears taking a called strike three on a pitch in a very similar location on August 31, 2017.
The new mandate not only affected ball and strike calls but also average game length. In 2016, the average KBO game lasted 3 hours and 23 minutes. In 2017? Just 3 hours and 17 minutes. It is perhaps noteworthy, as well, that for the first month of the season, the average game length was 3 hours and 12 minutes, a whole 11 minutes shaved off the previous mark. That seems even more significant! So, hypothetically, the strike-zone change could be a practical short-term solution to quicken games.
There is a nagging question, though — namely, what happened after that first month? If we compare April to the rest of the season, we do see differences in strikeout rate and called-strike rate
2017 KBO Ball-Strike Numbers
The five-minute jump between April and everything after that seems significant enough to demand an explanation. Two theories are often invoked. The first is that hitters got acclimated to the change, decided to adapt a more aggressive approach, and produced. The second is that the umpires gradually went back to the previous strike zone.
The first theory is going to take some numbers to support. The wider strike zone bumped up the strikeout rate and reduced the walk rate throughout the league. As you see below, there were definitely more called strikes. As a result, hitters became a bit more aggressive.
Strike-Ball Numbers, KBO
Given the changes, more strikeouts, fewer walks, and more swings are to be expected. Hitters hit .272/.339/.400 in April and .289/.357/.447 from May till the end of the season. And most importantly, for the league’s purposes, here are the overall league slash lines:
The new strike-zone measure, while initially helping with the pace of play, did little to address the run-scoring environment. You could argue that the new strike zone encouraged hitters to be more aggressive and resulted in more balls put in play. The league 2017 BABIP of .327 is not much of a change from .326 and .331 from the previous two seasons. As the slugging percentage would indicate, the power did not die down either. In fact, the home-run total increased from 1,483 to 1,547. All in all, after a blip in the first month, the hitters simply continued to rake, and the game length regressed back to the norm.
The second point however, is partially confirmed. As the new rule was implemented, it became clear that pitches that did not touch the strike zone boundaries were often called strikes. In a mid-July interview, Kim Poong-Gi admitted that they “tweaked” the strike zone to make it smaller than it was in April. “Because the strike zone was overly wide in April, we adjusted it a bit smaller,” Kim said, “but we are still enforcing the wider strike zone width.” If that is true, then the numbers may back up the correlation. In April, the league ERA was at 4.46. It increased to 4.63 in May and saw a dramatic rise in June to 5.64.
That brought attention to a new problem: consistency. It can be hard enough to enforce a new measure. It gets harder when every umpire has a different zone.
The wide-strike-zone experiment, for now, is still an experiment in the KBO. Kim Poong-Gi announced in December that the league will continue to use wider strike zone in 2018. It’s very doubtful that it will solve the run-scoring issue in 2018 with the current pool of hitting and pitching talent in the KBO. Regarding pace of play, it would be easier to conclude something meaningful if there wasn’t such a disparity between the first month of game and the rest of the season’s. Other factors might account for some of the change in game length. Given the fluctuating game length trend and the overall inconsistencies, one could say that the strike-zone change created more problems that it solved. Does that mean that MLB should ditch the idea completely? Not necessarily. If the umpires can enforce a consistently sized zone throughout the season and give the players a good idea what to expect, then it could be executed decently.
Of course, another thing to note is that, throughout the baseball history, the strike-zone rules have changed multiple times. The regulation was not passed on a stone tablet like the Ten Commandments. It has been a product of adjustments according to the environment. For instance, in 1968, The Year of the Pitcher, MLB experienced an all-time pitcher-friendly season during which hitters slashed a mere .237/.299/.340 overall, with pitchers thriving to the tune of a 2.98 ERA. In 1969, the league responded by reducing the strike-zone size. In 1987, the league saw a then-record 4,458 home runs in a season. MLB adjusted the strike zone before the 1988 season by increasing the size. So it goes. The odds are that we will see another strike-zone change in future. Whether it will be for the pace of play remains to be seen.
All stats from Statiz unless otherwise specified.