[Choi Min-gyu's Baseball Prism] Bank of Korea Raises Interest Rates, KBO Expands S Zone

Central Bank to Deploy Policy Measures Like Interest Rate Hikes if Inflation Occurs
KBO Strike Zone Adjustments Similar, Expanding Zone to Aid Pitchers
If Zone Is Narrower or Wider Than Rules, Someone Gains 'Unfair Advantage'

[Image source=Yonhap News]

The professional baseball season, which opened on the 2nd, has held ninety-eight games as of the 25th. This accounts for 13.6% of the entire schedule. A clear characteristic is emerging: a "pitchers' duel." Pitchers, who have long been suppressed by hitters, are now showing strength. The league's average earned run average (ERA) is 3.41, the fifth lowest among forty-four pennant races. It is the lowest in 29 years since 1993 (3.27).

The number of strikeouts and walks is a good indicator to assess the balance between pitching and hitting. This year, batters are struck out an unprecedented number of times. The strikeout rate, calculated as strikeouts divided by plate appearances, is 19.3%, the highest ever. The walk rate (walks/plate appearances) is 8.5%, the eleventh lowest in history. This contrasts with last year's record high of 10.5%. The only other year with a walk rate decrease of more than 2.0 percentage points until last year was 2002 (-2.1%).

Although not every year, April, the early part of the season, generally favors pitchers over hitters. Pitchers aim to have their pitching abilities, such as velocity, at 100% for the opening game. Hitters' swing senses improve only after becoming somewhat accustomed to the pitchers' pitches. Even considering this, the pitchers' duel in April this year is very pronounced. It is highly likely to continue throughout the season. There is a clear reason driving this pitchers' duel.

The KBO expanded the strike zone this season. Until last year, the upper part of the zone was lower than the definition in the baseball rules. Especially, the courses at the far left and right edges were about one and a half baseballs (approximately 7.3 cm in diameter) lower. This put pitchers at a disadvantage. This is closely related to the reason why walks were issued at the highest frequency in history last year.

[Image source=Yonhap News]

Central banks use policy tools such as raising benchmark interest rates when inflation occurs. The Korea Baseball Organization (KBO) has used strike zone adjustments as a similar tool. When an inflation of excessive scoring occurs, the strike zone is expanded to benefit pitchers.

Before this year's professional baseball season opened, I participated in the publication of the professional baseball scouting report and tracked changes in the KBO strike zone over the years. Starting from 1990, there have been nine changes up to this year. The results were enviable even to the Bank of Korea. The KBO's policy tool of changing the strike zone worked very well. The theoretical direction is that when the zone expands, walks and scoring decrease, and when it shrinks, they increase. In the first season when the zone change was implemented, including this year, walks per nine innings all moved in the theoretical direction. Except for 1996, the ERA decreased in seasons when the zone expanded and increased when it shrank.

However, the effect did not last long. The KBO expanded the zone four consecutive times in 2010, 2015, 2017, and this year. The phrase "four consecutive times" clearly shows that the zone expansion was not effective. The intended effect appeared in the first year but faded over time. Around the latter part of the season, there was invariably talk on the field that "the zone has returned to its original state."

In the five games held on the 23rd, there were two batter ejections. LG Twins' Kim Hyun-soo and Samsung Lions' Jose Pirela were ejected after protesting the umpire's strike zone calls. Fans who see their beloved players being ejected from the game direct their criticism at the umpires. Frequent protests make umpires reluctant to make aggressive strike calls that disadvantage batters. This is known in psychology as the "omission bias." The batter's benefit is the pitcher's disadvantage. However, pitchers are physically farther from umpires than batters. The disadvantage of opposing an umpire's judgment is much greater for pitchers, who only face a few plate appearances per game, than for batters. The pressure from batters on umpires is stronger than that from pitchers.

[Image source=Yonhap News]

The strike zone is an invisible virtual space. There are individual differences among umpires, pitchers, and batters. One can hypothesize that a tacit agreement on the shape of the zone has been formed over the long history of baseball games. Until last year, the KBO League's zone was lower on the upper side compared to the rule-defined zone. Domestic players and umpires learn from amateur levels that "high pitches = bad pitches." It is not easy to accept a "bad pitch" as a "pitch to hit (strike)." The psychological factor among people on the field is likely related to why the zone expansions since 2010 ultimately failed.

Unlike in the past, the KBO now has means to evaluate strike zone calls. The tracking system installed in professional baseball stadiums measures the coordinates of where the pitch lands using radar and cameras. Major League Baseball has succeeded in using this system to align the actual strike zone almost exactly with the rule-defined zone. The KBO has not achieved this. There was also a policy error in prioritizing "consistency" over accuracy in umpire evaluations. Whether an umpire's call matches the rule-defined zone implemented by tracking data is evaluated by accuracy. Consistency checks whether the umpire makes the same call on the same course regardless of alignment with the rule-defined zone. Prioritizing consistency makes it difficult to realize the original intent of "calling the zone according to the rules."

The KBO has made progress this year by prioritizing accuracy over consistency from the zone expansion onward. This is a clear advancement. However, it will be equally necessary to convince people on the field of the need to improve the "tacit zone" they have acquired. If the zone is narrower or wider than the rules, someone gains an "unfair advantage." This goes against the purpose of professional sports, which is to attract fans to the stadium by raising skills through fair competition.

Director, Korean Baseball Society