Stats Glossary

Plain English explanations of baseball statistics, from counting stats to advanced analytics

Traditional Hitting Traditional Pitching Advanced Hitting Advanced Pitching Diamond Analytics

Traditional Hitting Stats

The classic counting and rate statistics you will see in any box score

Games Played

The number of games in which a player appeared.

Plate Appearances

Every time a batter completes a turn at the plate, whether by getting a hit, walking, striking out, or any other outcome.

At Bats

Plate appearances minus walks, hit by pitches, sacrifice bunts, sacrifice flies, and catcher interference. The denominator for batting average.

Hits

Any time the batter safely reaches base after putting the ball in play, without the benefit of an error or fielder's choice.

Doubles

Hits where the batter reaches second base.

Triples

Hits where the batter reaches third base. Relatively rare because they require both power and speed.

Home Runs

Hits where the batter rounds all bases and scores. Either the ball leaves the playing field or the batter circles the bases on an inside-the-park hit.

RBI

Runs Batted In

The number of runs that score as a direct result of the batter's action, excluding runs scored on errors or double plays.

Runs

The number of times a player crosses home plate to score.

Stolen Bases

Successful attempts to advance a base while the pitcher delivers to home plate.

Walks (Base on Balls)

Reaching first base after four balls are called by the umpire during an at-bat.

SO/K

Strikeouts

An out recorded when three strikes are called on a batter.

AVG

Batting Average

The rate of hits per at-bat. A .300 average (3 hits per 10 at-bats) is considered excellent.

Formula: H / AB

Good: .270+

OBP

On-Base Percentage

How often a batter reaches base. Includes hits, walks, and hit by pitches. More valuable than batting average because walks have value.

Formula: (H + BB + HBP) / (AB + BB + HBP + SF)

Good: .340+

SLG

Slugging Percentage

Total bases divided by at-bats. Measures power by weighting extra-base hits more heavily.

Formula: Total Bases / AB

Good: .450+

OPS

On-Base Plus Slugging

The sum of on-base percentage and slugging percentage. A quick way to measure overall offensive contribution.

Formula: OBP + SLG

Good: .800+

Traditional Pitching Stats

Standard pitching metrics that have been tracked for over a century

Wins

Credited to a starting pitcher who pitches at least 5 innings and leaves with their team ahead (and the lead is never relinquished), or to the relief pitcher of record when the winning run scores.

Losses

Charged to the pitcher who allows the go-ahead run that the other team never relinquishes.

Saves

Credited to a relief pitcher who finishes a game for the winning team under specific circumstances (protecting a lead of 3 runs or fewer, or entering with the tying run on base or at bat).

Innings Pitched

The number of outs recorded divided by 3. Displayed as whole innings plus thirds (e.g., 6.1 means 6 innings plus 1 out).

Games Started

The number of games in which the pitcher was the starting pitcher.

ERA

Earned Run Average

The average number of earned runs allowed per 9 innings. Does not include runs that score due to errors.

Formula: (Earned Runs / IP) * 9

Good: 3.50 or lower

WHIP

Walks + Hits per Inning Pitched

Measures how many baserunners a pitcher allows per inning. Lower is better.

Formula: (BB + H) / IP

Good: 1.20 or lower

Strikeouts

The number of batters retired via strikeout.

Walks Allowed

The number of batters who reached base via walk.

Advanced Hitting Stats

Modern metrics that better capture true offensive value

wOBA

Weighted On-Base Average

A comprehensive offensive metric that weights each way of reaching base by its actual run value. More accurate than OPS because it properly values walks, singles, doubles, etc.

Formula: (0.69*BB + 0.72*HBP + 0.89*1B + 1.27*2B + 1.62*3B + 2.10*HR) / (AB+BB+SF+HBP)

Good: .340+

wRAA

Weighted Runs Above Average

The number of runs a player contributes beyond what a league-average hitter would produce with the same number of plate appearances.

Formula: ((wOBA - lgWOBA) / 1.15) * PA

Good: Positive = above average

ISO

Isolated Power

Measures raw power by looking only at extra-base hits. Removes singles from the equation to focus purely on power.

Formula: SLG - AVG

Good: .180+

BABIP

Batting Average on Balls in Play

Batting average on balls hit into the field of play (excluding home runs and strikeouts). Useful for identifying luck. League average is around .300.

Formula: (H - HR) / (AB - SO - HR + SF)

Good: .290-.310 (league avg)

Strikeout Rate

The percentage of plate appearances that result in a strikeout. Lower is generally better for hitters.

Formula: SO / PA

Good: 20% or lower

BB%

Walk Rate

The percentage of plate appearances that result in a walk. Indicates plate discipline.

Formula: BB / PA

Good: 10%+

BB/K

Walk to Strikeout Ratio

The ratio of walks to strikeouts. A higher ratio indicates better plate discipline and contact ability.

Formula: BB / K

Good: 0.50+

Advanced Pitching Stats

Metrics that isolate pitcher performance from factors outside their control

FIP

Fielding Independent Pitching

Estimates what a pitcher's ERA should be based only on events the pitcher directly controls: strikeouts, walks, hit batters, and home runs. Removes the influence of defense.

Formula: ((13*HR)+(3*(BB+HBP))-(2*K))/IP + 3.10

Good: 3.50 or lower

Strikeout Rate

The percentage of batters faced who strike out. Higher is better for pitchers.

Formula: SO / BF

Good: 25%+

BB%

Walk Rate

The percentage of batters faced who walk. Lower is better for pitchers.

Formula: BB / BF

Good: 7% or lower

K-BB%

Strikeout Minus Walk Rate

The difference between strikeout rate and walk rate. A simple but effective measure of pitcher dominance.

Formula: K% - BB%

Good: 15%+

HR/9

Home Runs per 9 Innings

The average number of home runs allowed per 9 innings pitched.

Formula: (HR / IP) * 9

Good: 1.0 or lower

K/9

Strikeouts per 9 Innings

The average number of strikeouts per 9 innings pitched. Measures a pitcher's ability to miss bats.

Formula: (K / IP) * 9

Good: 9.0+

BB/9

Walks per 9 Innings

The average number of walks allowed per 9 innings pitched. Measures control.

Formula: (BB / IP) * 9

Good: 3.0 or lower

Diamond Analytics Proprietary Metrics

Our custom metrics designed to evaluate and rank players comprehensively

Diamond Score

Diamond Score (0-100)

A proprietary composite score that evaluates a player's overall value and projection. Incorporates production metrics, age relative to level, and tool grades. Higher scores indicate better players.

Good: 75+ (Starter), 85+ (All-Star), 95+ (MVP)

Diamond Value

Diamond Value (WAR-lite)

An estimated wins above replacement value. For hitters, combines wRAA (offensive runs), baserunning runs, and an age adjustment. For pitchers, uses FIP-based run prevention.

Formula: Hitters: (wRAA + BR Runs + Age Bonus) / 10

Good: 2.0+ (starter), 4.0+ (All-Star)

Tool Grades

Tool Grades (20-80 Scale)

Baseball's traditional scouting scale where 50 is average. Each 10 points represents roughly one standard deviation. Hitters are graded on Hit, Power, Speed, and Discipline. Pitchers are graded on Stuff, Command, Results, and Stamina.

Good: 50 (Avg), 60 (Plus), 70 (Plus-Plus), 80 (Elite)

Level Adj

Level Adjustment

Diamond Score applies a multiplier based on the level of competition. Lower levels (A ball) get lower multipliers because production against weaker competition is less indicative of MLB success.

Good: A: 0.65x, A+: 0.75x, AA: 0.85x, AAA/MLB: 1.0x

Diamond Score Tiers

How we classify players based on their Diamond Score

MVP(95+)

Historic/MVP caliber. The best of the best, top 1-3 players in baseball.

All-Star(85-94)

All-Star caliber. Franchise cornerstones and perennial award contenders.

Starter(75-84)

Above average starter. Consistent contributors who anchor a lineup or rotation.

Average(65-74)

Average MLB player. Solid regulars you can count on every day.

Below Avg(55-64)

Below average. Platoon players, back-end roster spots, or developing talent.

Replacement(Below 55)

Replacement level. Freely available talent or organizational depth.