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Baseball Glossary
Learn the language of Baseball — answer-first definitions with real examples, beginner to pro.
51 terms
- Attack Angle (Batting)AdvancedAttack angle in batting is the vertical angle of the bat path through the hitting zone. A slightly upward attack angle matches the pitch plane for hard contact. Statcast treats 5 to 20 degrees at contact as the ideal range.
- Attack DirectionAdvancedAttack direction is the left-to-right direction the bat's sweet spot is moving at contact, measured in degrees toward the pull side or the opposite field from a line to straightaway center. The MLB average is about 2° pull, and most hitters' season averages fall between about 15° pull and 10° opposite field. It mostly reflects timing: an early swing points the bat toward the pull side, and a late one toward the opposite field.
- Backdoor Breaking BallAdvancedA backdoor breaking ball starts off the plate and breaks back over the outside corner for a called strike. It looks like a ball until the last instant.
- BarrelAdvancedA barrel is a batted ball with both high exit velocity and an optimal launch angle. That combination is the one most likely to produce extra-base hits.
- Barrel AccuracyAdvancedBarrel accuracy is how reliably a hitter finds the bat's sweet spot rather than the handle or end cap. It differs from the formal "barrel" stat.
- Blast (Bat Tracking)AdvancedA blast is a Statcast bat-tracking term for a swing that is both fast and squared up. A swing counts as a blast when its squared-up percentage times 100, plus its bat speed in mph, is at least 164. It rewards hitters who combine bat speed with solid contact.
- Called Strike RateAdvancedCalled strike rate is the share of in-zone pitches a hitter takes for a strike. It mirrors chase rate, measuring missed chances instead of bad swings.
- Called-Strike-Plus-Whiff Rate (CSW%)AdvancedCSW% is called strikes plus swinging strikes (whiffs) as a share of all pitches thrown. It shows how often a pitcher gets a strike without a ball in play.
- Chase ContactAdvancedChase contact rate is the percentage of swings at pitches outside the strike zone that make contact. It shows how well a hitter survives a swing at a bad pitch.
- Collapsing Back SideAdvancedCollapsing the back side is when the back knee and hip buckle and drop instead of staying stacked. It robs ground force and leaves the arms to do the work.
- Cut FastballAdvancedThe cutter is a fastball with late glove-side movement — harder than a slider, smaller break than a slider — that jams or cuts away from hitters.
- Diving Catch TechniqueAdvancedDiving catch technique is how a fielder extends fully, glove-first and parallel to the ground. It is a last resort for a ball just out of running range.
- Drag BuntAdvancedA drag bunt is a bunt started while already moving toward first base, usually by a lefty. It aims to beat out a hit, not sacrifice an out.
- Early Connection and Connection at ImpactAdvancedEarly connection is a swing-sensor metric for the angle between the hitter's body tilt and the bat's vertical angle as the downswing starts. One sensor maker targets about 90 degrees, within roughly 80 to 105. Connection at impact is the same relationship at contact. Together they show whether the barrel starts and stays in a strong position.
- Eephus PitchAdvancedThe eephus is a very slow, high-arcing pitch thrown with little arm speed, often 30-40 mph slower than a fastball. It is built to disrupt a hitter's timing.
- Effective VelocityAdvancedEffective velocity is the idea that how fast a pitch feels depends on location, not just the radar gun. Inside pitches feel faster, outside and low ones slower.
- Expected Stats (xBA, xSLG, xwOBA)AdvancedXBA, xSLG and xwOBA are Statcast's expected stats. They estimate what a hitter's batting average, slugging and wOBA should be, based on how hard and at what angle each ball was hit. On some weakly hit balls, sprint speed is added. Because they remove the defense, they show contact quality better than the real results.
- Fast-Swing RateAdvancedFast-swing rate is the share of a hitter's swings with a bat speed of 75 mph or more. Statcast picked 75 mph because that is about where production per swing reaches league average. It shows how often a hitter swings hard, not just how hard their fastest swing is.
- Framing a PitchAdvancedFraming is how a catcher receives a borderline pitch so it looks like a strike. The catcher uses soft hands and sticks the pitch where it arrives.
- Front Door Breaking BallAdvancedA front door breaking ball starts at a same-handed batter as if it might hit them. Then it breaks back over the inside corner for a strike.
- Ground Ball vs Fly Ball TendencyAdvancedGround ball versus fly ball tendency is the overall shape of a hitter's batted balls. It shows whether their attack angle produces grounders, fly balls, or a mix.
- Hand Cast Distance (Bat Sensor Metric)AdvancedHand cast distance is a bat-sensor metric for how far your hands drift away from your body during the swing. Diamond Kinetics measures how far the hands move sideways from their load position at the start of the swing to where they are at impact. A large number can be a sign of casting.
- Hard-Hit RateAdvancedHard-hit rate is the percentage of batted balls struck above a set exit-velocity threshold — usually 95 mph in MLB, scaled lower for amateur levels. It measures contact quality independent of luck.
- In-Between HopAdvancedThe in-between hop is an awkward bounce at shin or knee height. It is too high to pick off the dirt and too low to field out front, a common cause of errors.
- Intercept Point (Statcast Contact Point)AdvancedIntercept point is Statcast's name for where the bat meets the ball. It is measured two ways: compared with the front of home plate and compared with the hitter's body. Hitters who make contact farther out in front tend to pull the ball in the air for power. Deeper contact suits all-fields hitters.
- Knuckle CurveAdvancedA knuckle curve is a curveball gripped with a bent finger pressed knuckle-first against the ball. It gives a tighter spin axis and a later, sharper break.
- On-Plane EfficiencyAdvancedOn-plane efficiency is a swing-sensor metric for the percentage of the swing in which the bat stays on the plane it will meet the ball on. A higher number means the barrel spends longer in line with the pitch. One sensor maker recommends an average of 70 percent or higher, within a range of about 65 to 85 percent.
- On-Plane SwingAdvancedAn on-plane swing travels along the incoming pitch's flight path through the hitting zone. This keeps the barrel and ball aligned for a longer window and converting timing errors into contact rather than misses.
- Peak Hand Speed (Swing Sensor)AdvancedPeak hand speed is the fastest the hands move during the swing, measured at the bat handle. One sensor maker measures it six inches from the knob, just before contact as the wrists unhinge. It feeds bat speed. Bat speed also depends on how well that hand speed is passed on to the barrel.
- Pitch SequencingAdvancedPitch sequencing is the art of ordering pitches to exploit a hitter's tendencies and set up future offerings — making each pitch more effective because of what came before.
- Pitch TunnelingAdvancedPitch tunneling is throwing different pitch types on the same early flight path so they separate late. The hitter can almost never tell them apart in time.
- Pitching DeceptionAdvancedPitching deception is any part of a pitcher's mechanics, grip, or delivery that delays or confuses the hitter. It disguises pitch type, speed, or location.
- Pop Time (Catcher)AdvancedPop time is the time from a pitch hitting the catcher's mitt to the throw reaching the glove at second base. It measures a catcher's throw on a steal attempt.
- Quick PitchAdvancedA quick pitch is a pitcher delivering the ball before the batter is set and ready in the box. It is an attempt to catch the hitter off guard that is illegal at most levels of play.
- Range FactorAdvancedRange factor is a traditional defensive stat: putouts plus assists per game (or per nine innings). It roughly estimates how much ground a fielder covers.
- Reading the Ball off the BatAdvancedReading the ball off the bat is judging a batted ball's path, speed, and landing spot just after contact. It uses bat angle and early flight, not the full arc.
- Rotational AccelerationAdvancedRotational acceleration is a swing-sensor metric for how quickly the bat accelerates into the swing plane early in the swing. It is reported in g's. One sensor maker lists an MLB average of 17 g and calls 15 g or more high. It reflects how well the body, not just the hands, starts the swing.
- Spin Rate (Pitching)AdvancedSpin rate is how fast the ball rotates in revolutions per minute (RPM) after leaving the hand — higher spin amplifies the Magnus effect and increases pitch movement.
- Splitter / ForkballAdvancedThe splitter is an off-speed pitch gripped with the fingers spread across the seams. This produces late diving action that generates weak contact or swings below the zone.
- Squared-Up RateAdvancedSquared-up rate measures how close exit velocity comes to the theoretical max for that swing and pitch. It tracks contact precision, not raw bat speed.
- Squeeze Play (Bunt)AdvancedA squeeze play is a called bunt to score a runner from third. The runner goes on the pitch in a suicide squeeze, or once the bunt is down in a safety squeeze.
- Swing LengthAdvancedSwing length is how far the barrel travels from the start of the swing to contact. A shorter path generally needs less time, at some cost to peak bat speed.
- Swing Path TiltAdvancedSwing path tilt is the angle of the bat's path compared with the ground, measured over the last 40 milliseconds before contact. Statcast puts the MLB average at about 32 degrees, with hitters ranging from about 20 to 50. A higher number means a steeper, more vertical swing plane.
- Swing Power (Sensor Metric)AdvancedSwing power is a sensor metric for the average power a hitter puts into the bat during the swing, reported in kilowatts. It combines the bat's effective mass, bat speed at impact and how quickly the bat accelerates on the downswing. Swinging a heavier bat faster raises it.
- Time to ContactAdvancedTime to contact is the split-second a swing takes from trigger to ball. It sets how late a hitter can afford to start swinging against a given velocity.
- Tools Grade Scale (20-80)AdvancedThe 20-80 scale is how scouts grade each of a player's tools. A 50 is Major League average, 80 is elite, and 20 is well below usable at the top level.
- Training to Hit VelocityAdvancedTo train for 90-mph pitching, shorten your reaction time in practice. Move a pitching machine or front-toss screen closer so a slower pitch arrives as fast as game speed. Track high-velocity pitches without swinging, too. Pair that with a short, quick swing and an earlier load, since you have less time to decide.
- Tunnel PointAdvancedThe tunnel point is the spot in a pitch's flight where two pitch types still share nearly the same path. It is roughly where the batter must decide to swing.
- Vertical Bat AngleAdvancedVertical bat angle is the tilt of the bat compared with level at contact. Zero means the barrel and knob are level, and a negative number means the barrel is below the hands. Almost every hitter reads negative. The number gets more negative on low pitches and less negative on high ones.
- Weighted On-Base Average (wOBA)AdvancedWeighted On-Base Average (wOBA) gives each hitting outcome a run value. It combines walks and hits into one rate that is scaled like on-base percentage.
- Zone Contact RateAdvancedZone contact rate is the share of swings at in-zone pitches that make contact. It is a core measure of bat-to-ball skill on pitches a hitter should handle.
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