Plain-English Definitions

Every betting + sabermetric term you'll see on Bookie Bullies, explained without jargon. If we use a word that isn't here, tell us and we'll add it.

Betting Markets

Moneyline ML

Straight pick on which team wins. Odds shown as +150 (bet $100 to win $150) or -130 (bet $130 to win $100). No spread, no total — just who wins.

Run Line RL

MLB's fixed spread, almost always ±1.5. The favorite wins by 2+ runs to cover (-1.5), or the underdog can lose by 1 run and still cover (+1.5). Pays close to even money on most matchups.

Spread NBA

NBA's variable spread, e.g. -7.5 means the favorite has to win by 8+. Set by the book to attract roughly equal action on both sides.

Total O/U

Over/Under on the combined final score. Over 8.5 means both teams' runs together total 9+. Doesn't matter who wins.

First 5 Innings F5

An MLB-only side market on just the first 5 innings of a game. Strips bullpen variance out — only the starting pitchers matter. Good when you trust an SP but not their bullpen.

F5 Total F5_OU

Over/Under on combined runs scored in the first 5 innings only. Typically lines around 4.0-5.5 runs.

Confidence + Edge

Win % prob

Our model's estimated probability that the pick wins, expressed as a percentage. A 60% pick is expected to win 60 times out of 100 over a long sample. Includes the "± X%" uncertainty band, which widens when the model and market disagree.

EV Expected Value

Average profit per unit wagered if our probability is correct. +5% EV means a $100 bet returns $5 profit on average over many repetitions. Anything positive means the model thinks we have an edge.

Edge

The gap between our win % and the de-vigged market implied %. If the market says a team wins 50% but we say 55%, our edge is +0.05. Sharp bettors hunt for any positive edge over a fair-priced market.

Stake

Recommended bet size in units (1u = 1% of bankroll by default). Computed via 1/8-Kelly — a fraction of the optimal Kelly criterion to reduce variance, since model probabilities aren't perfect.

Stars (★)

Confidence tier from 1-5 derived from final probability + edge. 5★ requires both ≥58% prob AND ≥4% edge over market. 4★ needs ≥55% prob.

Lock

A 5★ pick where the model strongly disagrees with market in our direction. Highest conviction call of the day. Note: locks lose too — frequently. There is no such thing as a guaranteed bet.

CLV Closing Line Value

The single most important metric for evaluating long-term skill. Measures whether our published odds beat the closing market line. Positive CLV over a large sample = you're +EV regardless of short-term wins/losses. We track and publish ours on the Track Record page.

ESPN Matchup Predictor

ESPN's in-house probabilistic model for each game. Surfaced on every Bookie Bullies side pick (ML / RL / spread) as a reference. Where our model and ESPN's agree, both are seeing the edge. Where they diverge by 10+ percentage points, one of us is wrong about that game. ESPN's number is shown for transparency, it doesn't vote, override, or shrink our model's call. The self-learning system tracks divergence vs outcomes over time so the brain can empirically learn whether disagreeing with ESPN predicts losses.

Bet-Tracked Pick

A pick logged with both real American odds and a Kelly-sized stake at pick time. Bet-tracked picks count toward Units P/L and ROI on the track record page. Picks logged before the Kelly staking system went live in late April 2026 count toward hit rate (the outcome is unambiguous) but not units. Every new pick from then on is bet-tracked.

Pick Permalink

Every graded pick gets a permanent URL at /picks/{date}/{id}.html with the matchup, our model probability at pick time, ESPN's comparison, the actual result, and a written retrospective. The URL never changes once logged. Citation-friendly, search-indexed.

MLB Stats

FIP Fielding Independent Pitching

Pitcher's ERA equivalent based only on outcomes they fully control: strikeouts, walks, home runs, hit-by-pitch. Strips out defensive luck. More predictive of next-start performance than raw ERA.

xFIP Expected FIP

FIP normalized to league-average HR/FB rate. Removes home-run-allowed luck on top of FIP's defensive-luck strip. The most predictive single pitcher metric.

fipMinus FIP-

FIP indexed to league average and adjusted for ballpark. 100 = league average, 90 = 10% better than league, 110 = 10% worse. Removes both park and league effects, so it's directly comparable across pitchers.

xERA

Statcast's quality-of-contact-derived ERA. Built from exit velocity + launch angle of every batted ball, predicts what ERA should be if outcomes converted at average rates. Less fluky than raw ERA.

wOBA Weighted On-Base Average

Single number summarizing offensive output per plate appearance, weighted by run value (a HR is worth more than a single, a walk less than a single). League average ≈ .320.

OAA Outs Above Average

Statcast's defensive metric — how many outs a fielder/team converted that an average defender wouldn't. +10 OAA = saved 10 hits over the season. Big team gaps swing 0.4 R/game.

Catcher Framing

Runs saved by a catcher's ability to "steal" extra strikes on borderline pitches. League ranges from +8 R / 150G (elite, like Posey) to -6 R / 150G. Translates directly to lower SP ERA.

Bullpen Quality

Team-level bullpen xERA, lower = better. A 3.20-xERA pen vs a 4.20 pen has roughly a 0.4 R late-game edge. We amplify this signal in close games (where the late innings matter most).

BABIP Batting Avg on Balls In Play

Hits ÷ (balls in play). League norm ≈ .300. A pitcher running .220 BABIP is getting lucky; expect regression toward .300 next start.

LOB% Left-On-Base %

Fraction of baserunners a pitcher strands. League norm ≈ 72%. A pitcher at 85% has been getting lucky with timing.

Park Factor

Multiplier vs neutral. Coors = 1.23 means Coors plays 23% above average for run scoring. We adjust totals using park factors specific to each park, plus separate by-handedness HR factors (Yankee Stadium boosts LHB HRs more than RHB).

NBA Stats

Net Rating

Points scored minus points allowed per 100 possessions. +5.0 net = elite; -5.0 = bottom-tier. Most predictive single team metric.

Pace

Possessions per 48 minutes. Faster pace → more possessions → higher totals. League avg ≈ 99-101.

ORtg / DRtg

Offensive / Defensive Rating — points scored or allowed per 100 possessions. Pace-adjusted versions of points per game.

VORP

Value Over Replacement Player. Used to estimate the run-scoring impact of an injury (e.g. Kawhi out = -3.5 VORP = ~5 pts off the team's expected score).

Four Factors

The four stats that explain ~90% of basketball outcomes: eFG% (effective FG%), TOV% (turnover rate), ORB% (offensive rebound rate), FTR (free throw rate).

Advanced + Quant

Skellam Distribution

The probability distribution of the difference between two Poisson variables. Used to compute MLB margin probabilities (home runs - away runs). The correct family for integer-count differences — most public models use Gaussian, which underestimates tail risk.

Negative Binomial

Used for MLB run total probabilities. Real run totals are overdispersed Poisson (variance > mean) because of streakiness. Negative Binomial models this; Gaussian doesn't.

Bayesian Uncertainty

The "± X%" next to each win probability. Computed from the spread between our model, market, ensemble, and closing-line components. Tight band = sharp consensus = high conviction. Wide band = strong disagreement = low conviction.

Kelly Criterion

The mathematically optimal stake size given win probability and odds: f* = (p·b - q) / b. We use 1/8-Kelly (1/8th of the optimal) because real probabilities have noise, and full Kelly amplifies estimation error catastrophically.

De-vigged Market Probability

Market odds with the bookmaker's vig (~4-5%) stripped out, leaving the "fair" probability the book actually believes. Computed as side_juice / (side_juice + opp_juice + vig_constant).

Steam Move

A sharp, sudden line movement caused by professional money hitting the market. We track this in line_movement.json and surface "steam with us" / "steam against us" as a model driver.

Closing Line

The final odds posted just before a game starts. The market's most accurate read since all available information has been incorporated. Beating the close consistently = positive long-term edge.

Brier Score

Standard calibration metric: mean squared error between predicted probability and actual outcome (0 or 1). Lower = better. A perfectly calibrated 60% pick that hits 60% of the time has Brier ≈ 0.24.

Last updated: 2026-05-08. See something missing? Email hello@bookiebullies.com.