The KBO's own rules

Most of what is written about baseball strategy was written about Major League Baseball. The arithmetic travels — an out is an out in Seoul — but the rules around it do not. The KBO calls balls and strikes by machine, runs a pitch clock, ends regular-season games tied after eleven innings, and caps how many imported players each club may carry. Each of those rules moves a decision somewhere the MLB textbook does not.

In 2024 the KBO became the first top-flight league to hand ball-and-strike calls to a tracking system. The zone is set for each hitter from his height, the call is relayed to the plate umpire through an earpiece, and it is the same in the first inning and the ninth, in Jamsil and in Changwon.

Three strategic consequences follow. Catcher framing — the art of stealing strikes at the edges, worth many runs a season to the best MLB catchers — is worth nothing, so a catcher is now judged on throwing, blocking, game-calling and his bat. The edges of the zone become a fixed target, which rewards pitchers with precise command over pitchers who relied on a generous umpire. And hitters can learn the zone exactly, which makes the two-strike take a skill rather than a gamble.

After a trial in 2024, the KBO's pitch clock became a full rule in 2025: a time limit between pitches, shorter with the bases empty. For strategy, the clock matters less as a stopwatch than as a constraint on the pitcher with a runner on. A pitcher who cannot hold the ball, step off at will or throw over freely gives the runner a better jump; in MLB, the limit on disengagements that came with the 2023 clock, more than the clock itself, is what revived the running game.

The KBO record shows no MLB-style surge. Attempts per team game ran 0.84 this season, against 0.99 in 2025, with success at 74.4%. With only four seasons on file and the clock arriving alongside other changes, the platform cannot separate its effect from everything else.

Since 2025 a KBO regular-season game that is level after eleven innings stops and goes in the book as a tie (the limit had been twelve). There is no runner placed on second to hurry things along. This season produced 17 ties in 720 finals. The win tables say that a game tied after nine ends tied 28% of the time, and a game still tied going into the eleventh ends tied 53% of the time.

That makes the eleventh inning a different game. In the bottom of the eleventh the home side cannot lose: it either scores and wins, or does not and ties. Its only objective is the chance of scoring at least once — 29% from a clean start — which is the purest case for the bunt, the steal and the pinch-runner in the sport. The visitors, pitching, are playing only not to lose; every reliever they own should be available, because there is no twelfth inning to save him for.

So a tie is not half a win, as the guide's win values assume for a .500 club. A strong club loses less by settling for one; a weak one gains less from scraping one. In a pennant race, a tie against the club directly ahead of you is a game you can no longer make up.

Each club may carry three import players, and from 2026 one more under the Asia quota, open to players from Asian countries and Australia. The slots are scarce, so clubs fill them where one player moves the most. This season import pitchers threw 30% of the league's innings while import hitters took 11% of its plate appearances. 49 of the 65 imports who played were pitchers. A front-line import starter faces more batters in a season than an everyday hitter has plate appearances, and none of his value is diluted by a defensive position. The import slot is, overwhelmingly, a rotation slot.

That shapes strategy downstream. A rotation anchored by two imports pushes the domestic arms into the bullpen and the back of the rotation; it is one reason KBO starters' workloads look the way they do in chapter six. And when an import gets hurt, the replacement rules and the scramble to sign someone mid-season are a real cost that a club's depth chart has to plan for.