Reference
Glossary
Stats you’ll see in answers with meanings, simple formulas, and why they matter.
53 terms
Arm Strength
StatcastThrow velocity (mph) on throws (often highlighted for outfielders).
Why it matters: Helps evaluate whether runners can take extra bases against that arm.
At Bats
BattingPlate appearances that count toward batting average (excludes walks, HBP, sac flies/bunts).
Why it matters: Used for AVG and SLG; smaller than PA, so rates can look different.
BABIP
BattingBatting average only on balls put in play (excludes homers and strikeouts).
Formula: (H − HR) / (AB − K − HR + SF)
Why it matters: Often regresses toward ~.300. Extreme BABIP can signal luck more than lasting skill.
Barrel
StatcastA batted ball with an ideal mix of exit velocity and launch angle, considered the sweet spot for damage.
Why it matters: Barrels become hits and extra-base hits at very high rates.
Barrel Percentage
StatcastShare of batted balls that qualify as barrels.
Formula: Barrels / Batted Ball Events
Why it matters: Normalizes barrel skill by opportunity. Better than raw barrel count alone.
Batting Average
BattingHow often a batter gets a hit per at-bat.
Formula: H / AB
Why it matters: The classic hit rate. Easy to read, but ignores walks and extra-base power.
Called Strike + Whiff Percentage
ApproachCalled strikes plus swinging strikes, as a share of all pitches.
Formula: (Called strikes + Swinging strikes) / Pitches
Why it matters: Strong all-in-one pitcher “stuff + command” proxy used a lot in modern scouting.
Caught Stealing
BattingFailed steal attempts where the runner is tagged out.
Why it matters: High CS undermines SB value.
Chase Rate
ApproachPercentage of swings at pitches outside the strike zone.
Formula: Out-of-zone swings / Out-of-zone pitches
Why it matters: High chase usually means weaker contact and more pitcher-friendly counts. Key plate-discipline read.
Contact Percentage
ApproachHow often swings result in contact (fair or foul), not a whiff.
Formula: Contact / Swings
Why it matters: Useful for contact-oriented hitters.
ERA
PitchingEarned runs allowed per nine innings.
Formula: (ER × 9) / IP
Why it matters: The headline pitching rate. Influenced by defense and sequencing; pair with FIP/WHIP for process.
Exit Velocity
StatcastHow hard the ball leaves the bat, in miles per hour.
Why it matters: Harder contact is more likely to become hits and extra-base damage. Core Statcast quality-of-contact metric.
Expected Batting Average
BattingEstimated batting average from how hard and at what angle the ball was hit.
Why it matters: Shows whether a batter’s hits are backed by strong contact quality.
Expected Slugging Percentage
BattingEstimated slugging from exit velocity and launch angle on contact.
Why it matters: Useful when actual SLG looks potentially fluky.
Expected Weighted On-Base Average
BattingWhat wOBA would look like based on quality of contact (exit velocity and launch angle), not the actual hit/out result.
Why it matters: Filters out luck and defense. Useful for spotting over- or under-performance vs. process.
FIP
PitchingEstimates pitching using outcomes pitchers control most: strikeouts, walks, HBP, and home runs.
Why it matters: Strips out balls in play luck. Useful when ERA and FIP disagree a lot.
Ground Ball / Fly Ball / Line Drive
ApproachHow batted balls are classified by trajectory. Rates are often shown as shares of balls in play.
Why it matters: Profile matter: GB-heavy pitchers suppress HR; FB hitters need enough EV to avoid easy outs.
Hard-Hit Percentage
StatcastShare of batted balls hit at 95+ mph exit velocity.
Formula: Hard-hit balls / Batted Ball Events
Why it matters: Simple contact-quality rate. Strong signal for lasting offense.
Hits
BattingTimes a batter reaches base safely on a ball in play without an error or fielder’s choice.
Why it matters: Raw counting total for contact success; pair with PA or AB for context.
Home Runs
BattingFair balls that leave the park in play for a score.
Why it matters: The highest-value hit outcome and a core power signal.
Innings Pitched
PitchingHow many innings a pitcher has thrown (outs ÷ 3).
Why it matters: Workload and sample size for every pitching rate.
Isolated Power
BattingExtra bases beyond singles — pure power rate.
Formula: SLG − AVG
Why it matters: Separates power from simply making contact for singles.
Launch Angle
StatcastThe vertical angle of the ball as it leaves the bat, in degrees.
Why it matters: Too low → grounders; too high → popups. Ideal ranges with high EV produce barrels.
Losses
PitchingGames credited as a loss under official scoring rules.
Why it matters: More narrative than evaluation.
Maximum Exit Velocity
StatcastThe hardest single batted ball a player has hit in the sample.
Why it matters: Shows raw power ceiling, not average contact quality.
On-Base Percentage
BattingHow often a batter reaches base by hit, walk, or hit-by-pitch.
Formula: (H + BB + HBP) / (AB + BB + HBP + SF)
Why it matters: Getting on base drives runs. Usually more informative than batting average alone.
On-Base Plus Slugging
BattingA simple combo of on-base skill and power.
Formula: OBP + SLG
Why it matters: Quick all-in-one offense snapshot. Not perfect, but widely used and easy to compare.
Outside-Zone Contact Percentage
ApproachContact rate on swings at pitches outside the zone.
Formula: Out-of-zone contact / Out-of-zone swings
Why it matters: Some hitters spoil chases; others expand and miss. Affects two-strike survival.
Plate Appearances
BattingEvery completed turn at the plate: hits, outs, walks, HBP, and sacrifices.
Why it matters: The usual denominator for rate stats and the fairest volume measure for hitters.
Runs Batted In
BattingRuns that score as a direct result of a batter’s plate appearance (with standard scoring rules).
Why it matters: Context-heavy and depends on runners on base. Better as a team/storytelling stat than pure skill.
Saves
PitchingRelief appearances that close out a win under save-rule situations.
Why it matters: Role-driven counting stat for closers; doesn’t capture setup or high-leverage work alone.
Season Filter
ProductThe year context FullCount uses for your question (from the season control in the header).
Why it matters: Stats change by season. Setting the year keeps answers aligned with the sample you care about.
Slugging Percentage
BattingTotal bases per at-bat. Rewards doubles, triples, and home runs.
Formula: TB / AB
Why it matters: Shows power production, not just how often someone hits.
Spin Rate
StatcastHow many times a pitch rotates per minute (rpm).
Why it matters: Affects movement and deception. Context matters by pitch type. Raw rpm isn’t always “better.”
Spray Chart
ProductA field diagram of where batted balls landed or were fielded: pull, center, and opposite field.
Why it matters: Shows pull tendencies, opposite-field power, and shift-relevant spray patterns.
Sprint Speed
StatcastA runner’s top speed in feet per second over their fastest one-second window.
Why it matters: Baserunning and defensive range proxy. Elite speeds stand out clearly on the leaderboard.
Stat Grid
ProductThe card-style summary of key numbers returned for many FullCount answers.
Why it matters: Quick scan of headline rates and counts before digging into charts or tables.
Statcast
ProductMLB’s tracking system that measures pitch and batted-ball data with radar and cameras (exit velo, launch angle, spin, and more).
Why it matters: It’s the foundation of modern pitch-level analysis in FullCount: quality of contact and pitch traits instead of just box scores.
Stolen Bases
BattingTimes a runner successfully advances a base on a steal attempt.
Why it matters: Adds baserunning value; pair with caught stealing to judge aggressiveness.
Strikeout Percentage
BattingShare of plate appearances that end in a strikeout.
Formula: K / PA
Why it matters: High K% can be fine with power, but it caps batting average and contact opportunities.
Strikeouts (pitcher)
PitchingBatters retired on strikes (looking or swinging).
Why it matters: Missed bats are a durable pitching skill and feed K% and Whiff rate.
Swing Percentage
ApproachOverall share of pitches a batter swings at.
Formula: Swings / Pitches seen
Why it matters: Baseline aggressiveness before splitting zone vs. chase.
Swinging Strike Percentage
ApproachSwinging strikes as a percentage of all pitches.
Formula: Swinging strikes / Total pitches
Why it matters: Pitcher miss-bat rate that includes taken pitches in the denominator.
Walk Percentage
BattingShare of plate appearances that end in a walk.
Formula: BB / PA
Why it matters: Measures patience and plate discipline without needing counting totals.
Walks (pitcher)
PitchingBatters awarded first base after four balls.
Why it matters: Free baserunners. High walk rates inflate WHIP and scoring risk.
Weighted On-Base Average
BattingA rate that weights each offensive outcome by how many runs it typically creates.
Formula: Run-weighted events / PA (scale varies by year)
Why it matters: Better than AVG or OPS for overall offensive value because walks, singles, and homers are not treated equally.
Whiff Rate
ApproachPercentage of swings that miss the ball entirely.
Formula: Swinging misses / Swings
Why it matters: For pitchers: swing-and-miss stuff. For hitters: contact weakness. Central to modern approach analysis.
WHIP
PitchingBaserunners allowed via hits and walks per inning pitched.
Formula: (BB + H) / IP
Why it matters: Traffic on the bases. Lower WHIP usually means fewer scoring chances.
Wins
PitchingGames credited as a win under official scoring rules.
Why it matters: Team- and bullpen-dependent. Fun for history; weak as a pure pitcher skill measure.
Zone Contact Percentage
ApproachHow often a batter makes contact when swinging at pitches in the zone.
Formula: Zone contact / Zone swings
Why it matters: In-zone miss problems show up here even if chase rate looks fine.
Zone Heatmap
ProductA FullCount chart showing where pitches or contact concentrate in and around the strike zone.
Why it matters: Makes location patterns obvious: hot zones, chase areas, and pitch targeting at a glance.
Zone Percentage
ApproachShare of pitches thrown in the strike zone.
Formula: Zone pitches / Total pitches
Why it matters: For pitchers: attack vs. nibble. For hitters: how often they see competitive strikes.
Zone Swing Percentage
ApproachHow often a batter swings at pitches in the strike zone.
Formula: Zone swings / Zone pitches
Why it matters: Aggression vs. patience in the zone. Pairs with chase rate for a full discipline picture.