the limits of the record · pure baseball · retrosheet 1903–2025

15,704,096 recorded plays.
45 legal pairs still missing.

A play, reduced to 14 pure-baseball attributes, occupies one cell in a space of 2.28 billion possible combinations. This is a map of what recorded major-league history has already written down—and what it has not.

How full is the space?

Coverage of every k-attribute combination, counting each subset of dimensions times each assignment of values. The naive denominator includes rule-impossible combos, so 100% is not actually reachable above k=1.

Every single value has occurred (k=1). Nearly every pair has. By k=5 the space is half empty — and the empty half is where the firsts live.

The pair map

All 91 dimension pairs. Green pairs are fully written. A hatched pair is missing only rule-impossible cells. Gold pairs still contain a legal, never-seen play — tap one to jump to its grid.

seen 1× → 10M× never — and legal impossible by rule

Where the gaps are

Every pair with at least one empty cell, as a heatmap: darker green = more of history landed there. Hover any cell for its count or its reason.

The white whales

All 45 legal-but-never pairs, in plain language. Six favorites, annotated:

An intentional walk that ends the game.

Bases loaded, tie game, bottom of the ninth — and the manager holds up four fingers anyway, walking in the winning run on purpose. Managers have issued bases-loaded intentional walks (Bonds, 1998). Never to lose.

The batter scores on his own strikeout.

Strike three gets away, and the batter rounds all the bases on the ensuing chaos — all within the one play. 15.7 million plays, zero times.

A strikeout with three errors charged.

A strikeout with two errors has happened. The third error remains unclaimed.

A triple play with an error on the play.

Three outs and a misplay on the same pitch. Every triple play ever recorded has been error-free.

A three-error play in the ninth inning or extras.

Three-error chaos exists — 33 plays of it, ever — but apparently late-inning defense has never fully melted down. (A #7 hitter drew the first three-error play of any kind only in 2025.)

The batter scores on a play that records two outs.

Two teammates cut down on the bases while the batter circles all the way home. Legal. Unwritten.

the other 39

Why it will never be finished

New combinations minted per decade — the discovery rate collapses by orders of magnitude, then rule changes (the DH in 1973, most visibly) crack the space open again. Note the vertical scale is logarithmic.

Two forces guarantee the space outlives us. First, the remaining cells are the product of individually rare values: a cell needing a three-error play (1 in ~476,000 PAs) in extra innings (1 in 46) from the nine-hole (1 in 10) waits roughly 220 million plate appearances — over a thousand seasons — and cells like that are the common end of what's left. Coverage under a heavy-tailed coupon collector grows logarithmically: each percentage point costs ~10× the plays of the last. Second, the target moves: 6–7% of every season's plate appearances are still full 14-tuples never seen before, and that rate has been rising since 2015. The book gets longer faster than it gets read.

Method: 15,704,096 regular + postseason plate appearances, Retrosheet 1903–2025 (incl. Federal League and Negro Leagues), reduced to the 14 core pure-baseball dimensions of mlb_firsts. "Possible" = Cartesian product of observed value spaces (RBI capped at 4 and errors at 3 by construction). Impossibility classifications are the project's invariant rules — arithmetic, dead-ball, and scoring-definition constraints only; everything else stays gold.