A field guide · KBO 2026
Strategy by the numbers
Eleven decisions a manager makes, each argued from first principles and then checked against this season's KBO record. When to bunt, when to run, when to walk a man on purpose, who bats second, when to go to the bullpen and which reliever to use — and how an automated strike zone, a pitch clock and an eleven-inning limit change the answers.
Runs per team game
5.07
Chance of a run, per inning
29%
One-run games
23%
168 of 720
Home side wins
51.5%
of decided games
Yardstick
Expected runs
How many runs the rest of the inning is worth. The right yardstick early, when every run counts the same.
Yardstick
The chance of a run
How likely the inning is to produce at least one. The right yardstick when one run is the game.
Yardstick
Win expectancy
The chance of winning from here, built for nine innings with extras to eleven and ties. The final word, late.
Part
The foundation
Part
Making runs
The sacrifice bunt
Trading an out for a base almost always costs runs. It can still win games — the difference is which question you are asking.
Read the chapter →
Stolen bases and the break-even rate
A steal is a bet with known odds. The base gained is worth less than the runner lost, so you have to win the bet often.
Read the chapter →
Lineup construction
Each step down the order costs about sixteen plate appearances a season. Where those go, and with whom on base, is the whole art.
Read the chapter →
Platoons and handedness
Hitters see the ball better from an opposite-handed pitcher. A league with three right-handed arms for every left-handed one is a league built for left-handed hitters.
Read the chapter →
Part
Running a staff
The times-through-the-order penalty
Hitters get better each time they see the same starter in a game. The hook should come from that curve, not from the pitch count alone.
Read the chapter →
Bullpen leverage and the closer
Some innings decide games and some do not. The save rule spends the best reliever on a three-run ninth and saves him from a tied eighth.
Read the chapter →
Counts, leverage and pitch sequencing
A plate appearance is a tree of twelve counts. Some pitches move the outcome a great deal, and the right mix is a mixed strategy.
Read the chapter →
Part
Saving runs
The intentional walk
Putting a man on base on purpose adds runs to the other side's ledger. Sometimes the hitter you avoid is worth it.
Read the chapter →
Defensive positioning
Where fielders stand is a trade between outs and runs. Drawing the infield in is the clearest case, and its answer depends on the scoreboard.
Read the chapter →
Part
The KBO's own game
On one page
The eleven short versions
- 01
Run expectancy and the 24 base-out states. An out is the scarcest thing an offence owns; a decision is good when the state it leads to is worth more than the state it leaves.
- 02
The sacrifice bunt. Bunt when one run is the whole game and the hitter at the plate is unlikely to do better; otherwise swing.
- 03
Stolen bases and the break-even rate. Run only when your chance of being safe clears the break-even line for that base, those outs and that score.
- 04
Lineup construction. Give the most plate appearances to the best hitters, and bat the very best second, where volume and runners on base meet.
- 05
Platoons and handedness. The platoon edge is real but smaller than the gap between good and bad hitters; use it to break ties, not to bench your best bat.
- 06
The times-through-the-order penalty. Pull the starter when his third-time-through self is worse than the reliever you would bring in, not when he reaches a round number.
- 07
Bullpen leverage and the closer. Use your best reliever in the highest-leverage inning you are likely to face, whatever it is called.
- 08
Counts, leverage and pitch sequencing. Win the pitches that swing the count most, and be unpredictable in exactly the proportions game theory prescribes.
- 09
The intentional walk. A walk is a gift unless the hitter you skip is far better than the one you get, or the extra force play buys you a win.
- 10
Defensive positioning. Play in when the runner on third matters more than the hits you will give up: always late and close, rarely early with nobody out.
- 11
The KBO's own rules. Read the textbook, then adjust it for the league you are in: a tie is a real result here, and the zone does not move.
Method
What the numbers can and cannot say
Every figure in this guide is computed from the KBO's own record for the 2026 season, through Oct 13, 2026, or labelled as a general figure from MLB research. The run and win tables are built by playing 40,000 half-innings from each of the 24 base-out states on this season's league-wide event rates; played from the start of an inning they reproduce the league's real scoring to within about a hundredth of a run.
What the public record does not hold bounds what can be said. There is no play-by-play, so baserunning advancement rates are borrowed from MLB and the tables are models rather than tallies. There are no splits by pitcher hand, no pitch-by-pitch counts, no batted-ball or positioning data, and no record of batting orders. Each chapter says which of those it runs into, in a note at the foot of the page.
Win values count a tie as half a win, which is exact for a .500 club; chapter eleven explains why, under the KBO's winning-percentage rule, a tie is really worth a club's own percentage.