---
name: baseball-rules
description: Resolves baseball rules questions, umpire rulings and official-scoring decisions for MLB, NCAA, high school (NFHS) and WBC play, with rule citations and the edge cases models usually get wrong. Use when a question turns on a baseball rule, umpire ruling, official scoring decision, or MLB vs college rule difference — infield fly, dropped third strike, balk, obstruction, interference, appeals, fourth out, ground-rule double, overthrow awards, hit vs error, earned runs, RBI, saves, wins, pitch clock, ABS challenge, extra-innings runner, DH, mound visits, shift rules.
---

# Baseball Rules

Editions used: MLB Official Baseball Rules (OBR) **2026**; MLB regulations that live outside the OBR text (pitch timer, ABS challenges, position-player pitching, two-way designation) as announced through the 2026 season; NCAA Baseball Rules **2027-28** (published Oct 2026, governs the 2027 and 2028 seasons; the 2025-26 book governed 2025 and 2026); NFHS from published change summaries only (the book is paywalled). Cite the rule number in every ruling.

## Procedure

1. **State the situation.** Level and season year; count; outs; runners; and where every runner was at two moments: the time of the pitch and the time of the act (contact, throw leaving the hand, interference, obstruction). Ask if any of these are missing and change the answer.
2. **Identify the governing rule.** Name it. Check the defined terms in OBR "Definitions of Terms" (Catch, Force Play, Infielder, Ordinary Effort, Tag, Touch, Obstruction, Interference). Rules that apply only with fewer than two outs, or only with specific bases occupied, are the usual trap.
3. **Live or dead ball.** Decide: dead immediately, delayed dead (play runs, umpire then nullifies), or live. Skipping this step causes most wrong answers.
4. **Apply the awards.** From which base (time of pitch, time of throw, last base legally touched), how many bases, which outs stand, and whether runs count (5.08(a) exception, 5.09(d)).
5. **Score it separately.** Rulings and scoring are separate decisions. A two-base award can be a hit (9.06(e)), an error (9.12(c)) or neither. See `references/scoring-rules.md`.

Say plainly when a call is umpire or scorer judgment (ordinary effort, intent, "attempt to avoid", would-have-scored). Tell the user to check the current rulebook when the season differs from the editions above, when a conference or tournament local rule may apply (NCAA run rule, NCAA extra-inning runner, NFHS state adoptions), for MLB regulations outside OBR (timer details, ABS), or for any NFHS specific.

## Rulings models get wrong

| Situation | Correct ruling | Rule |
|---|---|---|
| Infield fly | Only with R1+R2 or bases loaded and fewer than 2 outs; fair fly (not a line drive or bunt) an infielder can catch with ordinary effort. Batter is out caught or not, so the force is removed: a runner who advances must be tagged. Ball live; runners advance at their own risk. If the ball is caught, they must retouch first, as on any caught fly, and a runner who left early can be put out on appeal. Can be called even if an outfielder makes the catch. Not an appeal play. | Definitions (Infield Fly), 5.09(a)(5); runner touched on his base: 5.09(b)(7) Exception |
| Dropped third strike | Batter may run only if 1B is empty, or with 2 outs. Otherwise out. A pitch that hits the ground first is not caught. A batter who leaves the dirt circle without running is out. | 5.05(a)(2), 5.09(a)(2)-(3) |
| Intentionally dropped fly | Fewer than 2 outs, 1B occupied: batter out, ball dead, runners return. Infield fly rule takes precedence when it applies. | 5.09(a)(12) |
| Hit by pitch | No award if the pitch is in the strike zone (strike) or the batter made no attempt to avoid it (ball or strike). Ball is dead either way, no runner advances. | 5.05(b)(2) |
| Catcher's interference | Batter to 1B, forced runners advance. Offensive manager may take the play instead; if the batter reaches and every runner advances at least one base, the play stands automatically. | 5.05(b)(3), 6.01(c) |
| Batted ball hits a runner | Runner out, ball dead, batter gets 1B and a hit, others advance only if forced. Exception: ball already past an infielder with no other infielder able to play, or deflected by an infielder. Runner on his base touched by an infield fly is not out. | 5.09(b)(7), 5.06(c)(6), 9.05(a)(5) |
| Runner hinders a fielder on a batted ball | Out whether intentional or not. If on a legally occupied base, out only if intentional; then both runner and batter are out with fewer than 2 outs. | 6.01(a) Penalty Comment |
| Obstruction | Play being made on that runner, or the batter-runner obstructed before touching 1B: dead immediately, runner gets at least one base past the last base legally touched. No play on him: ball live, umpire nullifies after the play; a runner going past the protected base does so at his own peril. | 6.01(h)(1), (h)(2) |
| Time play vs force play | On the third out, runs that crossed before it count unless the out is the batter-runner before 1B, a force out, or a preceding runner out on a missed-base appeal. A runner doubled off after a catch is not a force out. | 5.08(a) |
| Fourth out | An appeal after the third out can replace it and erase a run. It must be made before the pitcher and all infielders leave fair territory. | 5.09(c) |
| Wild throw out of play | 2 bases. From the time of the pitch only on an infielder's first play when not all runners (batter-runner included) had advanced a base; otherwise from when the throw left the hand. | 5.06(b)(4)(G) |
| Pitch out of play | Pitch, or throw from the rubber, straight into stands or dugout: 1 base. Lodged in the catcher's or umpire's gear: 1 base. | 5.06(b)(4)(H), 5.06(c)(7) |
| Ground-rule double vs fan | Bounding fair ball into the stands: 2 bases. Spectator interference is different: dead ball, umpire places runners to nullify it, may call the batter out on a prevented catch. No interference when the fielder reaches into the stands. | 5.05(a)(6), 6.01(e) |
| Balk | Dead ball, each runner advances one base, unless the pitch lets the batter reach 1B and every runner advance at least one base. Bases empty, an illegal pitch is a ball. | 6.02(a), (b) |
| Batting out of order | Appeal only; umpire stays silent. Proper batter is out; advances from the improper batter's ball in play are erased; steals, balks, WPs and PBs stand. Pitch to the next batter legalizes it. | 6.03(b) |
| Walk-off hit | Batter credited only with the bases the winning run needs, if he runs them. Over-the-fence home runs are the exception: all runs count. | 9.06(f), (g) |

## MLB items that change by year

| Item | Current rule (year) | Source |
|---|---|---|
| Pitch timer | 15 s bases empty, 18 s runners on (2024); 2 free disengagements per PA, third is a balk unless an out results | MLB regulation, not in OBR |
| ABS challenge | 2 per team, kept on success; pitcher, catcher or batter only (2026) | MLB regulation |
| Mound visits | 4 per 9 innings, +1 per extra inning, +1 in the 9th if none left (2024) | 5.10(m), 2024 regulation |
| Three-batter minimum | Face 3 batters or end the inning | 5.10(g) |
| Extra innings | Automatic runner on 2B from the 10th; not in the postseason; runner is unearned | 7.01(b)(2) |
| Shift limits | 4 players on the infield dirt, 2 each side of 2B, no switching sides (2023) | 5.02(c) |
| Bases | 18-inch square (2023) | 2.03 |
| Two-way player | Listed as both SP and DH; can stay as DH after leaving the mound | 5.11(b) |

## Scoring quick hits

- Earned runs: rebuild the inning without errors and passed balls; benefit of the doubt to the pitcher (9.16).
- When an error with two outs stops the play that would have been the third out, every later run that inning is unearned (9.16(a) Comment). An error that only gives a runner an extra base doesn't end the inning; rebuild it.
- RBI is credited on an error when, with fewer than two outs, the runner from third would ordinarily have scored (9.04(a)(3)).
- No RBI on a ground-ball double play (9.04(b)).
- A sac fly is not an at-bat but is in the OBP denominator. A sac bunt is in neither (9.02, 9.21(f)).
- Starter win needs 5 IP in a game of 6 or more innings (9.17(b)).
- Save needs: finishing pitcher in a win, not the winner, at least 1/3 IP, and one of: entered with a lead of 3 runs or fewer and pitched 1 inning; tying run on base, at bat or on deck; or pitched 3 innings (9.19).
- A quality start is not an official statistic.

## Which reference to open

- `references/edge-cases.md` — the full ruling detail. Open it for:
  - interference and obstruction types, plus their awards;
  - appeals and the fourth out;
  - force vs time plays and run-scoring;
  - every base award (thrown ball, pitched ball, detached equipment, ground-rule);
  - balk list, pitch timer, mound visits, DH and the Ohtani rule, position players pitching.
- `references/scoring-rules.md` — any Rule 9 question:
  - hit vs error;
  - earned runs, including inherited runners, walk counts at a pitching change and reliever vs team earned runs;
  - RBI, SB/CS and defensive indifference, WP vs PB;
  - sacrifices, win/loss/save/shutout, ERA and OBP formulas.
- `references/levels.md` — anything outside MLB:
  - NCAA bats, run rule, extra-inning runner, action clock, slide rule, HBP, balk differences, P/DH, conferences, double first base;
  - NFHS;
  - the 2026 World Baseball Classic;
  - a rule-year table.