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Baseball Glossary
Learn the language of Baseball — answer-first definitions with real examples, beginner to pro.
132 terms
- Age vs Level (Scouting)IntermediateAge vs level weighs a player's stats against how old they are for their level. Being young for a level is generally good; being old tempers strong numbers.
- Arm AngleIntermediateArm angle is the vertical orientation of the throwing arm at release — from over-the-top through three-quarter, sidearm, to submarine — and it shapes both the pitch plane and movement profile.
- Arm Slot (Fielding)IntermediateA fielder's arm slot is the arm angle at release when throwing. The natural slot produces the most accurate and arm-safe throw for that player's anatomy.
- BABIP (Batting Average on Balls in Play)IntermediateBABIP is batting average on balls in play: hits that are not home runs, divided by the balls a hitter puts in play. The formula is (H − HR) ÷ (AB − K − HR + SF). League average is almost always around .300. Line drives fall for hits more often than ground balls, and ground balls more often than fly balls. As a result, hard line-drive contact helps. But short streaks are mostly luck.
- Backhand FieldIntermediateFielding a ground ball backhand means turning the back of the glove hand toward the ball. The fielder reaches across the body instead of squaring up.
- Backspin (Batting)IntermediateBackspin is backward rotation on a batted ball from contact slightly below center. Its Magnus effect helps fly balls and line drives carry instead of diving.
- BalkIntermediateA balk is an illegal or deceptive motion by the pitcher with runners on base. Every runner is immediately awarded one base, and no pitch needs to be thrown.
- Ball TransferIntermediateBall transfer is the exchange of the ball from glove to throwing hand. Its speed and consistency are among the biggest separators for infielders and catchers.
- Barrel PathIntermediateBarrel path is the route the barrel takes through the hitting zone. Matching it to the pitch plane as long as possible gives the best odds of hard contact.
- Baseball IQIntermediateBaseball IQ is a player's game awareness and decision-making, apart from physical tools. It is knowing where to throw, when to run, and how to position.
- Baserunning ReadIntermediateA baserunning read is the split-second decision a runner makes based on what the ball does after contact — whether to advance, hold, or retreat.
- Bat DragIntermediateBat drag is a sequencing fault where the hands race ahead and the barrel trails behind. It costs bat speed and forces contact deep, off the sweet spot.
- Bat Sensor AccuracyIntermediateBat sensors are fairly accurate for bat speed but less so for swing angles. A 2022 study compared four commercial sensors with a motion-capture system. Swing speed agreed well, swing angles agreed less, and every sensor had some built-in bias. Use one sensor to track your own trends rather than to compare brands or players.
- Bat SpeedIntermediateBat speed is how fast the barrel is moving at contact, in mph. It contributes to exit velocity alongside bat path and where on the barrel you make contact.
- Bat Speed by AgeIntermediateBlast Motion, a bat-sensor maker, publishes practice-swing ranges of about 30–45 mph for 8- to 10-year-olds and 40–52 for 11- to 12-year-olds. For older players its ranges are about 46–62 mph at 13–14, 55–65 at 15–16 and 60–70 at 17–18. Treat them as rough guides from one sensor in tee and toss work. In MLB, Statcast's average swing was about 72 mph when bat tracking launched in 2024.
- Batted Ball Event (BBE)IntermediateA batted ball event is any batted ball that produces a result: a hit, an out or an error. Every fair ball counts, and so does a foul ball caught for an out. Other foul balls do not count. Statcast uses batted ball events to figure average exit velocity, launch angle, hard-hit rate and barrel rate.
- Batting Out of OrderIntermediateIf you bat out of order, nothing happens unless the other team appeals. If they appeal while the wrong batter is still up, the right batter steps in and takes over the count. If they appeal after the wrong batter finishes but before the next pitch. The proper batter is out and any advance from the hit is cancelled. Once the next pitch is thrown, the wrong at-bat stands.
- Batting Practice StructureIntermediateGood batting practice gives every round a goal. Many coaches move from tee and toss to machine or live pitching, and from set locations to mixed ones. Rounds focus on one job, such as opposite-field line drives, bunts or a two-strike approach. Competitive rounds that score hard contact add game pressure.
- Blocking a Pitch (Catching)IntermediateBlocking is when a catcher smothers a pitch in the dirt with the body and chest protector, not the glove. It keeps the ball in front, preventing a passed ball.
- Carry (Throw)IntermediateCarry is how well a throw holds its speed and straight line without tailing, sinking, or losing steam. A throw that "carries" arrives true to the target.
- Casting (Batting)IntermediateCasting is a swing fault where the hands and barrel arc wide instead of taking a direct path to the ball. It kills bat speed and limits inside coverage.
- Catcher's InterferenceIntermediateCatcher's interference is when the catcher, or any fielder, interferes with the batter during a pitch, usually by touching the bat with the mitt as the batter swings. Under MLB Rule 6.01(c), the batter is awarded first base. If a play follows, the offense's manager can choose to take the result of the play instead.
- Ceiling vs Floor (Scouting)IntermediateCeiling is a player's realistic best-case outcome; floor is the realistic worst case if development stalls. Scouts weigh both, not just the exciting one.
- Changeup (Pitching)IntermediateThe changeup is an off-speed pitch thrown with fastball arm speed but held deeper in the hand to reduce velocity by 8–15 mph, disrupting timing.
- Chase RateIntermediateChase rate is the percentage of pitches thrown outside the strike zone that a hitter swings at. A core plate-discipline metric where lower is almost always better.
- Check SwingIntermediateA check swing is a swing the hitter stops before the bat crosses the plane of contact. It counts as a swing if the bat and wrists broke toward the ball.
- Chicken Wing (Hitting)IntermediateIn hitting, a chicken wing is when the front elbow lifts and bends out at contact instead of extending through the ball. It is usually a problem. It often comes from pulling off the ball or a rushed turn, and the barrel cuts across and leaves the zone early. A bent front arm on an inside pitch is normal, though.
- Circle Changeup GripIntermediateThe circle changeup grip forms a circle with the thumb and index finger on the side of the ball. It is built to cut velocity without changing arm speed.
- Command vs. ControlIntermediateControl means throwing enough strikes to avoid walks; command means locating a pitch to a precise spot within the zone. A pitcher can have one without the other.
- Common Hitting InjuriesIntermediateCommon hitting injuries include oblique (side) strains, hook of the hamate fractures in the hand, low back trouble and sore wrists. They often follow sudden jumps in swing volume, poor warm-ups or a body area that lacks strength or mobility. Stop swinging if something hurts, and see a qualified medical professional for pain that persists.
- Contact Point (Batting)IntermediateContact point is where the bat meets the ball, relative to the body and plate. It shifts with pitch location, and a fixed one is a common cause of weak contact.
- CurveballIntermediateThe curveball is an off-speed breaking pitch with topspin that makes it arc downward, often sharply, as it crosses the plate.
- Defensive RangeIntermediateDefensive range is how much ground a fielder can cover and convert into outs. It combines first step, speed, reads, and athleticism.
- Designated Hitter (DH)IntermediateIn high school baseball, NFHS Rule 3-1-4 allows a designated hitter in two ways. The DH can be a tenth starter who bats for one of the nine fielders. Or one of the nine starting fielders can also be the DH, playing defense and batting. In MLB, the DH bats only for the pitcher.
- Double Play PivotIntermediateThe double play pivot is a middle infielder's footwork at second base to catch a throw and fire it to first. It must be quick and avoid the sliding runner.
- Down-and-In Swing PathIntermediateA down-and-in swing path has the barrel dropping and cutting toward the body instead of staying on the pitch's plane. It yields weak pull-side grounders.
- Drifting and Swaying (Hitting)IntermediateDrifting is when the head and hips keep sliding toward the pitcher before the swing turns. Swaying is when the hips slide back past the back foot during the load. Both move the eyes and steal rotation. Many coaches fix them by loading into the inside of the back leg and keeping the head centered until the front foot lands.
- Drop Step (Outfield)IntermediateA drop step is an outfielder's first move on a ball hit over their head or into a gap. The back foot pivots, opening the hips on the most direct running angle.
- Dropping the Back ShoulderIntermediateDropping the back shoulder is a fault where the rear shoulder tilts down during the swing. It steepens the bat path and often causes an uppercut and pop-ups.
- Exit Velocity (EV)IntermediateExit velocity is how fast the ball comes off the bat, in mph. It is a ceiling metric — the harder you hit it, the farther it can go.
- Exit Velocity by AgeIntermediateThere is no official exit-velocity standard by age, and charts online disagree widely for any given age. Compare a reading only with ones taken under matching conditions: drill, device and bat type. As a top-level reference, MLB's Statcast counts a ball hit 95 mph or harder as hard-hit.
- Extension at ContactIntermediateExtension is the arms straightening through and just past contact, not folding in. At impact the rear arm usually keeps some bend, especially on inside pitches.
- First StepIntermediateFirst step is how quickly a fielder starts movement toward a batted ball — often the largest separator between good and great defenders.
- First-Pitch Swing RateIntermediateFirst-pitch swing rate is how often a hitter swings at the first pitch (0-0) of a plate appearance. It is a simple measure of early-count aggressiveness.
- First-Step QuicknessIntermediateFirst-step quickness is how fast a fielder's first move reacts off the bat. It is widely seen as the biggest factor in range, more than sprint speed.
- Five-Tool PlayerIntermediateA five-tool player is a position player rated above average in all five scouting tools. The tools are hitting for average, power, speed, arm, and fielding.
- Front Shoulder Flying OpenIntermediateThe front shoulder flies open when it turns toward the pitcher too early. That pulls the eyes and barrel off the ball, causing weak, pulled contact or a miss.
- Front-Leg Brace (Firm Front Side)IntermediateA front-leg brace is the lead leg firming up, often close to straight, as the swing turns. It stops the body's forward move and turns it into rotation. Many hitters land with a slightly bent knee and then push into the ground so the leg is firm by contact. It should not be locked stiff the moment the foot lands.
- Glove PresentationIntermediateGlove presentation (for catchers) is how the catcher holds and moves the mitt to receive the pitch cleanly and, in competitive baseball, to subtly show the umpire the ball in the strike zone.
- Grip and Core Strength for HittersIntermediateGrip strength is useful for hitting, but it is not the main source of bat speed. Most swing power starts in the legs, hips and trunk. A strong grip and forearms help you control the bat and hold the barrel steady at contact. Core and anti-rotation work helps you turn hard and stay balanced.
- Ground Ball RateIntermediateGround ball rate (GB%) is the percentage of batted balls that are grounders — usually a negative indicator for power hitters, though contact hitters may use it strategically.
- Hand PathIntermediateHand path is the route the hands travel from launch position to contact. A direct, efficient path keeps the barrel in the zone longer and prevents casting.
- Head Movement (Batting)IntermediateHead movement is excess drift, bob, or tilt of the head during the swing. A moving head makes it harder to track the ball and find the barrel reliably.
- Hip and Thoracic Mobility for HittersIntermediateHip and upper-back (thoracic) mobility let a hitter turn the pelvis and shoulders separately and hold posture through the swing. Tight hips can limit how far the pelvis turns at landing. A stiff upper back can limit shoulder turn during the load. Short, regular work such as 90/90 switches and open-book rotations helps many hitters.
- Hip Rotation (Batting)IntermediateHip rotation is the hips turning hard toward the pitcher to start the swing. It is the engine of rotational power, firing before the hands or barrel move.
- Hit-and-RunIntermediateA hit-and-run is a called play where the runner breaks with the pitch and the hitter must swing and make contact. Ideally a ground ball protects the runner.
- Hitch in the SwingIntermediateA hitch is an extra dip of the hands, down or back, after the load has started forward. It creates a second, unplanned load that costs time against velocity.
- Hitting a ChangeupIntermediateTo hit a changeup, land your front foot softly and keep your weight and hands back after you land. The pitch looks like a fastball out of the hand but arrives slower, and it often fades and sinks. Read the slower arm or spin early, let it get deep and drive it up the middle or the other way.
- Hitting a CurveballIntermediateTo hit a curveball, pick it up early from the hump and spin out of the pitcher's hand. Keep your weight and hands back, let the ball travel and hit it where it ends up, usually up the middle or the other way. Lay off a curve that starts at the knees. It usually finishes in the dirt.
- Hitting in Sun, Wind and Under LightsIntermediateUnder the lights, pick up the ball early at the pitcher's release and keep your head still. This is because the background can be darker and shadows can shift. In bright sun, shade your eyes with your cap brim and ask the umpire for time if glare blinds you. In wind, aim for hard line drives, since wind blowing in knocks fly balls down.
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