Batting · Headline & Rate
PA-denominated rate stats and league-relative indices.
| Abbr |
Name |
Meaning |
| PAVG |
Plate Average |
Hits divided by plate appearances (H / PA). O27's headline batting average — denominated by PA rather than AB so the 2C mechanic doesn't distort it. |
| BAVG |
Batting Average |
Traditional hits per at-bat (H / AB). Shown alongside PAVG; the gap between them (Δ2C) is the value added by Second-Chance at-bats. |
| AVG |
Batting Average |
Alias of PAVG (H / PA) in the native view. On the leaderboard's MLB-Equivalent (XO) cards it's the crossover-scaled value; natively O27 leads with PAVG. |
| OBP |
On-Base Percentage |
Rate of reaching base safely, PA-denominated: (H + BB + HBP) / PA. |
| SLG |
Slugging Percentage |
Total bases per plate appearance (TB / PA) — weights extra-base hits by their base value. PA-denominated like the rest of O27's rate stats, so it reads cleanly across multi-hit 2C at-bats. |
| OPS |
On-Base Plus Slugging |
OBP + SLG. A quick one-number read of overall offensive production. |
| OPS+ |
OPS Plus |
OPS relative to league average, scaled so 100 = league average and higher is better. |
| ISO |
Isolated Power |
SLG − PAVG (both PA-denominated) = extra bases per plate appearance. Measures raw extra-base power, stripping out singles. |
| BABIP |
Batting Avg on Balls in Play |
Hit rate on balls put in play (excludes HR and strikeouts). High values can signal good contact or good luck. |
| wOBA |
Weighted On-Base Average |
O27-tuned linear weights, PA-denominated. Each offensive event is weighted by its run value, then scaled to the OBP range. |
| wOBA+ |
wOBA Plus |
wOBA relative to league average (100 = average, higher = better). |
| wRC+ |
Weighted Runs Created Plus |
Park-adjusted, league-relative offense. 100 = league average at this park; >100 = better than league after stripping park bias. |
Batting · Power & Counting
Raw totals.
| Abbr |
Name |
Meaning |
| HR |
Home Runs |
Home runs hit. |
| RBI |
Runs Batted In |
Runs driven in by the batter. |
| H |
Hits |
Total hits. |
| R |
Runs |
Runs scored. |
| SB |
Stolen Bases |
Bases stolen successfully. |
| FO |
Foul-Outs |
Times the batter was retired under the O27 3-foul rule (three fouls in a PA = out). A subset of total outs, tracked separately from strikeouts. |
| FO% |
Foul-Out Rate |
Foul-outs per plate appearance (FO / PA) — how often a hitter fouls himself out. O27-specific; lower is better for the batter. |
Batting · O27-Native (Second Chance)
The load-bearing O27 mechanic: on a contact event the batter may take a second chance (spend a strike from their AB budget) instead of running.
| Abbr |
Name |
Meaning |
| 2C |
Second-Chance ABs |
Contact events where the batter took a second chance (spending a strike) instead of running. The signature O27 decision. |
| 2C-H |
Second-Chance Hits |
Hits credited on 2C events (a subset of total H). |
| 2C-Conv% |
Second-Chance Conversion % |
Fraction of 2C events that credited a hit. Talent-weighted by the batter's eye vs the pitcher's command on subsequent swings. |
| 2C-RBI |
Second-Chance RBI |
RBI driven by 2C events — surfaces 2C-mechanic specialists. |
| 2C-RBI% |
Second-Chance RBI Share |
Share of the batter's total RBI that came from 2C events. |
| Δ2C |
2C Average Lift |
BAVG − PAVG; quantifies the hit value added by the Second-Chance mechanic. |
Batting · Runner Advancement
How well a batter moves the runners already on base. The starting base refers to where the runner began the PA, NOT the hit type.
| Abbr |
Name |
Meaning |
| 1B% |
Advance from First % |
Rate at which the runner who started on FIRST advanced to a higher base or scored during this batter's PA. |
| 2B% |
Advance from Second % |
Rate at which the runner who started on SECOND advanced to third or scored during this batter's PA. |
| 3B% |
Advance from Third % |
Rate at which the runner who started on THIRD scored during this batter's PA — the pure RBI-conversion metric. |
| All% |
Overall Advancement % |
Overall advancement rate across all PAs with any runner on base. Composite of 1B%/2B%/3B% weighted by opportunity. |
| RAD |
Runners Advanced |
Total bases gained by runners during this batter's PAs. The runner-movement analogue of MLB Total Bases. |
Batting · Small Ball (Bunting)
Bunting production across four play types — sacrifice, bunt-for-hit/drag, and the suicide & safety squeeze. Calls are driven by a player's bunt rating (bat control, distinct from foot speed) and the manager's run-game tendency.
| Abbr |
Name |
Meaning |
| SH |
Sacrifice Hits |
Successful sacrifice bunts — a plate appearance (not an at-bat) that traded an out to advance a runner. Includes a scoring squeeze. |
| Bunt H |
Bunt Hits |
Bunt singles — drag bunts, sacrifices beaten out, or a squeeze legged out. A subset of total hits. |
| Bunts |
Bunt Attempts |
Total bunt plate appearances across all four types. |
| Sqz |
Squeeze Plays |
Squeeze attempts with a runner on third (suicide or safety). |
| Sqz RBI |
Squeeze RBI |
Runs driven home from third base on a squeeze bunt. |
Batting · Clutch (RISP)
Performance with runners in scoring position — a runner on 2B and/or 3B at the plate appearance's start. The recorded-outcome companion to the engine's RISP-pressure model: how well a bat actually cashes runners in. PA-denominated, like the headline rates (per-AB RISP rates are unreliable in O27 because a single AB can credit multiple hits via stays).
| Abbr |
Name |
Meaning |
| RISP-AVG |
Batting Average with RISP |
Hits per plate appearance with a runner in scoring position (H/PA). |
| RISP-OBP |
On-Base with RISP |
(H + BB + HBP) / PA in RISP situations. |
| RISP-SLG |
Slugging with RISP |
Total bases per PA in RISP situations. |
| RISP-OPS |
OPS with RISP |
RISP-OBP + RISP-SLG — the headline clutch-hitting rate. |
| RISP-RBI |
RBI with RISP |
RBI driven in while a runner was in scoring position. Typically the large majority of a hitter's RBI. |
| RISP-Conv |
RISP Cash-In Rate |
RBI per plate appearance with RISP — how often a RISP chance is converted into a run driven in. |
Fielding
PO/E credited per fielder via position-weighted attribution on each ball in play.
| Abbr |
Name |
Meaning |
| PO |
Putouts |
Outs recorded as the primary fielder on a play. |
| A |
Assists |
Throwing outs and double/triple-play chain pivots. |
| TC |
Total Chances |
PO + A + E — total fielding opportunities. |
| RF |
Range Factor |
(PO + A) × 27 / outs the fielder's team played. Higher = more involvement per inning. |
| FldPct |
Fielding Percentage |
(PO + A) / (PO + A + E). Share of chances handled cleanly. |
| E |
Errors |
Misplays charged to the fielder. Lower is better. |
| DRS |
Defensive Runs Saved |
Runs a fielder saved (or cost) relative to an average defender at the position. |
Power Play / Short-handed
Optional-rule stats, populated in leagues that enabled the Power Play (the fielding manager may deploy a 10th defender — the nickel fielder — for a short use-or-lose window). 'Power Play' is the deploying defense and the pitcher it backs; 'short-handed' is the offense facing it a man down — much like NHL power-play / penalty-kill splits.
| Abbr |
Name |
Meaning |
| PPD |
Power Plays Deployed |
Windows this player started as the nickel fielder (the 10th defender). |
| PPO |
Power Play Outs |
Outs the nickel's deployment windows covered — the time he was on the field. |
| XBHH |
Extra-Base Hits Held |
Doubles/triples the nickel cut down to singles by covering the outfield gap while deployed. |
| HC |
Hits Converted |
Shallow outfield singles the nickel ran down and turned into outs while deployed. |
| NF-PO |
Nickel Putouts |
Putouts recorded while playing as the nickel fielder (position NF). |
| SH-AVG |
Short-handed Average |
Batting average (hits / at-bats) for plate appearances taken while the opposing defense had its nickel fielder deployed. |
| SH-H |
Short-handed Hits |
Hits recorded against a deployed nickel fielder. |
| SH-PA |
Short-handed Plate Appearances |
Plate appearances taken while the opposing defense had its nickel deployed. |
| PP-BABIP |
Power Play BABIP-against |
Batting average on balls in play allowed while the pitcher had the nickel deployed behind him. Lower means the loaded defense suppressed more hits. |
| BABIP Δ |
Power Play BABIP Split |
PP-BABIP minus the pitcher's BABIP-against without the nickel. Negative = the 10th fielder lowered his BABIP-against. |
| PP-K% |
Power Play Strikeout Rate |
Strikeouts per batter faced while the nickel was deployed. Defense-independent — strikeouts never reach the extra fielder. |
| PP-BB% |
Power Play Walk Rate |
Walks per batter faced while the nickel was deployed. Defense-independent (lower is better). |
| PP-Cov% |
Power Play Coverage |
Share of the pitcher's total outs recorded with the nickel behind him — how often the manager has the extra fielder out there for this arm. |
| PP-BF |
Power Play Batters Faced |
Batters faced with the nickel deployed behind him. |
| H-Saved |
Hits Saved Behind Him |
Singles the nickel ran down for outs while this pitcher was on the mound. |
| XBH-Saved |
Extra-Base Hits Saved Behind Him |
Extra-base hits the nickel held to singles while this pitcher was on the mound. |
Pitching · Result-Tier
O27's run-prevention trio. The 27-out structure and lineup-cycling make raw ERA misleading, so these correct for arc position and contact quality.
| Abbr |
Name |
Meaning |
| wERA |
Weighted ERA |
Earned runs weighted by arc position (outs 1-9 ×0.85, 10-18 ×1.00, 19-27 ×1.20), league-anchored to raw ER/27. Lower is better. |
| wERA+ |
Weighted ERA Plus |
Park-adjusted, league-relative wERA on the ERA+ scale (100 = average, higher = better). |
| xRA |
Expected Runs Allowed |
Non-negative linear-weights estimate of runs allowed (HR≈1.4, single≈0.45, BB/HBP≈0.32), anchored so league xRA = league wERA. Lower is better. |
| RA/27 |
Runs Allowed per 27 Outs |
All runs allowed (earned + unearned) on the same 27-out scale as wERA/xRA — the runs-allowed sibling of ERA. Because it includes Walk-Back and passed-ball runs that ERA excludes, the RA/27 − wERA gap surfaces the run damage the earned-run stats hide. Lower is better. |
| Decay |
Late-Arc Decay (Fatigue) |
The FATIGUE/arc axis: drift-corrected fade in K% from arc-1 (outs 1-9) to arc-3 (outs 19-27). 0 = matches league norm; positive = fades worse; negative = holds up better. Measures how the long arc wears a pitcher down. The separate FAMILIARITY axis — how a lineup times him up across repeat looks — is the Deception grade + Times-Through-the-Order splits (almanac). Lower is better. |
| Dec |
Deception Grade |
20-80 scouting grade for how un-timeable a pitcher's arsenal stays across a 27-out arc, from the repertoire-weighted timing-resistance of his pitches. Knuckle / eephus / softball-junk arms grade high (un-timeable); pure-velocity arms grade low (figured out by the 4th look). 50 = league-neutral. The familiarity-axis complement to Decay's fatigue axis. |
| GB% |
Groundball Rate |
Share of balls in play hit on the ground (launch angle < 10°). Now genuinely pitch-driven via per-pitch launch-angle bias — sinkers, peeled drops and drop knucks run high; riseballs and rise knucks run low. Paired with LD%/FB% and GO/AO (groundout-to-airout ratio) as the batted-ball profile. |
| TTOk |
Times-Through K-Decay |
K% points lost from the 1st time facing a hitter in a game to the 3rd+ time, from engine-side times-through-the-order counters (the FAMILIARITY axis, sibling to Decay's fatigue axis). Positive = the lineup figures him out across repeat looks; ~0 / negative = he holds his whiffs as familiarity grows (the deception arbitrage). A small-sample split — meaningful in aggregate / over a full season. |
| TTOΔ |
Times-Through Hard-Hit Δ |
The contact-quality companion to TTO K-Decay: change in hard-hit% allowed from the 1st to the 3rd+ look (from the batted-ball log). Positive = hitters square him up more with familiarity. |
| LateK% |
Late K Rate |
Arc-3 K% (outs 19-27, including foul-outs). The short-relief sibling to Decay for arms that never see arc-1 sample. |
| GSc+ |
Game Score Plus |
League-relative Game Score (100 = league average, higher = better). |
| GSc Index |
Game Score Index |
Z-score-normalized Game Score on a 100/15 scale. Accounts for the spread of pitcher talent, so it's comparable across league sizes. |
| FOP |
Fielding-Omitted Pitching |
Fielding-independent pitching index on a 0–100 scale (50 = league average, higher = better). The DIPS sibling of Game Score: built only from the true outcomes a pitcher controls (K + foul-outs, BB + HBP, HR), so defense and BABIP luck never touch it — the 'O' nods to O27's native foul-outs, folded into the strikeout term. Bounded, so a dominant short outing caps near 100 instead of running off the scale the way a raw rate would. Underlying value is a foul-out-inclusive DIPS ERA squashed to 0–100. |
| DIPS-ERA |
DIPS ERA (FO-inclusive) |
Fielding-independent ERA-scale estimate behind FOP: (13·HR + 3·(BB+HBP) − 2·(K+FO)) / IP + league constant. Like FIP but credits O27 foul-outs as strikeouts, and anchored so league DIPS-ERA equals league ERA. Lower is better. |
Pitching · Workload & Stuff
Per-appearance volume and dominance.
| Abbr |
Name |
Meaning |
| GSc avg |
Game Score (avg) |
Average per-appearance Game Score (50 = neutral, 100 = perfection). |
| OS+ |
Outs Share Plus |
League-relative outs per appearance (100 = average). A workload index. |
| GE |
Game Equivalents |
Total workload expressed in complete-game-worths (one full O27 game = 27 outs), so total_outs / 27. The Out-Share-native synthetic workload number; synthetic IP is just GE × 9. |
| K% |
Strikeout Rate |
(K + foul-outs) / batters faced. O27 K% counts foul-outs as strikeouts. |
| BB% |
Walk Rate |
Walks per batter faced. Lower is better. |
| K-BB% |
K minus BB Rate |
(K − BB) / batters faced. A quick-read dominance signal. |
| FO% |
Foul-Out Rate |
Foul-outs induced per batter faced (FO / BF) — how often a pitcher fouls hitters out. The foul-out slice of the K% blend; higher is better. |
Pitching · Counting & Value
Raw totals and wins above replacement.
| Abbr |
Name |
Meaning |
| W |
Wins |
Wins credited. An SP earns it with ≥12 outs and the lead; otherwise the most-effective reliever. |
| K |
Strikeouts |
Strikeouts recorded. |
| FO |
Foul-Outs Induced |
Batters the pitcher retired under the O27 3-foul rule. Tracked separately from strikeouts, though K% folds the two together. |
| Outs |
Outs Recorded |
Pitcher workload in outs (one full O27 game = 27). |
| WAR |
Wins Above Replacement |
Total value over a replacement-level player, in wins. Uses an O27-fitted runs-per-win factor (~21 vs MLB's ~10). |
Pitching · Walk-Back & Arsenal
O27-specific rules and pitch-mix usage.
| Abbr |
Name |
Meaning |
| Walk-Back Stop% |
Walk-Back Stop Rate |
Strand rate for the rule-placed Walk-Back runner. After every HR, the next PA can drive home the HR-hitter from 3B for an extra unearned run. Higher = better. |
| FB% |
Fastball Usage |
Share of typed pitches that were fastballs (4-seam / sinker / cutter). |
| BR% |
Breaking-Ball Usage |
Share of typed pitches that were breaking balls (slider / curve / screwball / gyroball / spitter / peeled drop). |
| OFF% |
Off-Speed Usage |
Share of typed pitches that were off-speed or deception junk (change / split / palm / knuckle / eephus, plus the softball-derived riseball, backhand change, sky eephus, and the slither / drop / rise knuckle variants). |
Pitching · Relief & Finisher
O27 has no innings and no save rule, so relief value is measured structure-agnostically: leverage at entry, cleanup of inherited runners, and run prevention in the heavy final arc — letting any usage pattern (a one-out specialist, a deep ladder, or a back-stage 'finisher-starter') be compared on the same footing.
| Abbr |
Name |
Meaning |
| IR-Stop% |
Inherited-Runners Stranded % |
Of the runners on base when this pitcher entered, the share he stranded: (IR − IR-scored) / IR. Higher = better. The one relief skill no rule structure can obsolete. |
| gmLI |
Entered Leverage |
Average Leverage Index at the moment he entered a game (first PA of each appearance). Shows who gets the high-stakes calls. 1.0 = league norm; >1 = disproportionately high-stakes entries. |
| Late ER/BF |
Late-Arc Run Prevention |
Earned runs allowed per batter faced in the final arc (outs 19-27) — the heavy-leverage third where close games are decided. Lower = better finisher, regardless of how many outs he threw. |
| TO |
Terminal Outs |
Outs recorded in a game he entered with a lead, never let be tied or lost, and finished. Scales with the role: a one-out closer gets ~3, a back-stage finisher-starter who seals the final third gets ~9+. The counting measure of who really closes games. |
| QF |
Quality Finish |
The inverse of a Quality Start: entered and sealed 9+ of the final outs while never trailing (lead or tie), regardless of save situation. Separates high-volume finishers from one-out specialists. |
| LRA |
Lead-Retention Average |
Of the games he entered with a lead, the share he held without letting it be tied or lost on his watch, on a 0–10 scale (a perfect 10.00 = never blew a lead; 8.50 = held 85% of them). Read against outs-per-appearance it splits short-relief specialists from back-stage starters. |
Pitching · MLB-Readable Rates
Familiar MLB-shaped rate stats. On the leaderboard these honor the XO Crossover toggle; the MLB-Equivalent section always shows the z-anchored version.
| Abbr |
Name |
Meaning |
| ERA |
Earned Run Average |
Earned runs × 27 / outs (O27's 27-out game). Lower is better. |
| WHIP |
Walks + Hits per IP |
(BB + H) per inning pitched. Lower is better. |
| K/9 |
Strikeouts per 9 |
Strikeouts per nine innings. Higher is better. |
| BB/9 |
Walks per 9 |
Walks per nine innings. Lower is better. |
| HR/9 |
Home Runs per 9 |
Home runs allowed per nine innings. Lower is better. |
| oAVG |
Opponent Batting Average |
Batting average of the hitters this pitcher faced. Lower is better. |
| oOBP |
Opponent On-Base % |
On-base percentage allowed. Lower is better. |
| oSLG |
Opponent Slugging |
Slugging percentage allowed. Lower is better. |
| oOPS |
Opponent OPS |
OBP + SLG allowed. Lower is better. |
| BABIP |
Opponent BABIP |
Batting average on balls in play allowed (excludes HR and strikeouts). |
Win Probability & Leverage
Built empirically from this league's own outcomes — every PA's pre/post state joined to the final result.
| Abbr |
Name |
Meaning |
| WPA |
Win Probability Added |
Sum of the win-probability swing across a player's PAs. Positive = the player moved the needle for his team. |
| LI |
Leverage Index (avg) |
Average leverage of the situations a player appeared in. 1.0 = league norm; >1 = disproportionately high-stakes spots. |
MLB-Equivalent (XO Crossover)
O27 rate stats z-anchored to MLB league mean and spread, so the numbers read like MLB stats while preserving rank order exactly. Formula: xo = MLB_mean + ((value − O27_mean) / O27_sd) × MLB_sd. XO is a reading layer — it never changes an underlying calculation. Counting stats (HR, RBI, K) have no XO equivalent and pass through unchanged.
| Abbr |
Name |
Meaning |
| XO |
Crossover |
The crossover scale itself. Any rate stat shown on the XO scale carries the same player ranking as its native version — only the number translates to an MLB-readable value. |
Longer-form explanations and formulas live in the project docs
(stats-reference.md, pitching-stats-027.md).