Betting glossary

A quick reference for the language of betting and player props. Where a term has its own deep dive, the definition links to it.

Core math

Expected value (EV) — the average profit or loss a bet would return if you made it many times, found by weighing the payout by the true probability. Positive EV means the price beats the real chance. See expected value and the EV calculator.

Implied probability — the win probability baked into a price. Convert any odds to a probability with the odds converter.

No-vig (fair) odds— the price with the house margin stripped out, revealing the market’s true estimate. See no-vig fair odds and the no-vig calculator.

Variance — the natural swing of results around the average. Even a good bet loses often in the short run. See variance and sample size.

Regression to the mean— the tendency of an extreme hot or cold streak to drift back toward a player’s true level. Our projections regress thin samples on purpose.

Sample size— how many observations you have. Small samples lie; a few great games aren’t a trend.

Closing line value (CLV)— beating the final price the market settles on before a game. Consistently getting CLV is the best sign you’re finding real edges.

Hit rate — how often an outcome has landed historically (e.g. a hitter clearing a given line). We show per-line hit rates on each prop page.

Odds & pricing

American odds — the +150 / −120 format: a positive number is the profit on a 100 stake; a negative number is the stake needed to win 100.

Decimal odds — the total return per 1 staked (e.g. 2.50). Convert formats with the odds converter.

Vig (juice)— the margin a sportsbook builds into its prices; it’s why both sides of a coin flip pay less than even money.

Hold— the book’s expected profit margin on a market, computed from both sides’ prices. Measure it with the hold calculator.

Line — the number a bet is set at (a total, a spread, or a prop threshold like Hits 1.5).

Mainline vs. alternate — the standard, most-bet line versus the longer/shorter alternates at adjusted prices. We rank only trustworthy mainline prices.

Bet types

Moneyline — a straight bet on who wins. Run line — baseball’s spread, almost always ±1.5 runs. Total (over/under) — a bet on combined runs versus a posted number.

Player prop— a bet on an individual’s stat line (hits, total bases, strikeouts). See MLB player props.

Parlay — multiple bets combined; all must hit, for a bigger payout and a bigger edge to the book. Correlated parlay— legs whose outcomes are linked (treating them as independent overstates the payout’s fairness). See the parlay calculator.

Hedge — betting the other side to lock in profit or cap a loss; size it with the hedge calculator. Arbitrage — covering all outcomes across books for a guaranteed small profit.

Push— a tie with the line; the stake is refunded (half-point prop lines like 1.5 can’t push). Unit — a standard bet size, usually 1% of your bankroll. Bankroll — the money set aside for betting; see bankroll management. Kelly criterion — a formula for bet sizing based on your edge; see the Kelly calculator.

MLB & model terms

Total bases — bases weighted by hit type (single 1 … home run 4); see total bases props. RBI — a run batted in; why it’s hard to model. Strikeout prop — a pitcher’s K total; see pitcher strikeout props.

Ballpark factor — how much a stadium boosts or suppresses scoring; see ballpark factors. Platoon split — the edge a hitter gets against an opposite-handed pitcher. BABIP — batting average on balls in play, a gauge of batted-ball luck.

DFS pick’em — a daily-fantasy product where you pick more/less on player lines at fixed payouts. Projection— our model’s estimate of a stat; the gap between it and the line, judged against the price, is the edge. See the edge board and our methodology.

It’s all informational analysis, not betting advice — please play responsibly, 21+ (or the legal age where you live). See responsible gambling.