The goal was to cut the travel distance of the baseball by lowering the coefficient of restitution. Players didn’t feel much difference during the exhibition matches, but now the official play balls of the KBO, the South Korean baseball league, are increasingly shaping the games of the local baseball league.
Most noticeable is the sheer number of homeruns. As of Sunday, KBO players hit a total of 200 homers in 125 games, an average 1.6 per game. This is a 34 percent drop from the average 2.44 homers per game last year when KBO pitchers had a particularly hard time against batters (1,756 homers in 720 games). KBO outfielders, who used to watch the ball flying over the fence last year, have become much busier this year. “Balls that would have flown over into the stand are falling right before the fence this year,” said Son Ah-seop, the right fielder of the Lotte Giants.
The effects of a lower coefficient are shown in various metrics. According to Sports2i, an official KBO data agency, the average speed of homers stood at 156.1km per hour last year. However, that has fallen to 154.5km/h this year. The bouncing velocity has decreased by 1.5km/h, affecting the probability of long-distance drives. “The ball was harder last year, so it made a sharp, lighter sound when hit, but it got softer, so it makes a heavier thud when hit,” explained Son Ah-seop.
The travel distance of homers has also dropped. The average distance of the 1756 homeruns last year was 118m, which enough to fly over the center fence of smaller stadiums such as Sajik Baseball Stadium or Gwangju Kia Champions Field. The average flying distance, however, fell to 115.6m this year. The share of long-distance homers that go over the center fence has halved from 15 percent (263) to 7.5 percent (15) this year.
The fall in travel distance means batters must hit more precisely. “A growing number of batters are training to hit harder rather than higher. This is because now it takes a more impactful contact and a higher speed to produce a homerun,” said Jang Seong-ho, a baseball commentator of KBSN. While the total number of homers has dipped, the share of pulled homers, an indicator of powerful hits, went up from 68 percent to 74 percent.
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