Glossary — every stat in plain English

Savant gives you the data. This page is the translation. One sentence per stat, no math degree required — and if a stat isn't listed here, we don't use it.

Defense

Outs Above Average: Outs Above Average — how many outs his defense added or cost versus an average fielder at his position.
Max Arm Strength: Maximum tracked throw speed in the field.

Expected stats (the 'deserved' numbers)

xBA: What his batting average should be based on the quality of his contact, ignoring luck and defense.
xSLG: What his slugging should be based on contact quality — the power version of xBA.
xwOBA: What a hitter's overall production SHOULD be, judged only on how hard and at what angle he hits the ball (plus Ks and walks) — the best single 'deserved results' number.
xERA: What a pitcher's ERA should be from the contact quality and strikeouts he actually allows, with luck and defense stripped out.
wOBA: Overall offensive production per plate appearance, weighting walks, singles, and homers by their real run value.

Contact quality

Avg Exit Velocity: Average exit velocity — how hard the ball leaves the bat.
Hard-Hit%: Share of batted balls hit 95+ mph.
Barrel%: How often he hits the ball with the near-perfect combination of exit velocity and launch angle — barrels become extra-base hits more than half the time.
Sweet Spot%: Share of batted balls launched between 8 and 32 degrees, the range where hits live.
Avg Launch Angle: Average launch angle — the vertical angle the ball leaves the bat at.

Bat tracking & swing mechanics

Avg Bat Speed: How fast the barrel is moving at contact — the engine of power. League average is about 72 mph.
Fast Swing Rate: Share of swings over 75 mph of bat speed — how often he swings with full intent.
Squared-Up% (per swing): How often he catches the ball flush, converting his bat speed into exit velocity.
Swing Length: How far the barrel travels to reach contact — longer swings mean more power and more whiffs.
Avg Attack Angle: The upward tilt of the bat's path at contact — steep means lift-seeking, flat means line-drive contact.
Ideal Attack Angle%: How often his bat is on the ideal upward path (roughly 5-20 degrees) at contact.
Swing Path Tilt: The overall tilt of the swing plane.
Contact Depth vs Plate: How far in front of the plate he meets the ball on average.
Depth in Box: Where he stands in the batter's box, front to back.
Avg Miss Distance: Average distance, in inches, between where he hit the ball and the bat's sweet spot.
Perfect Swing%: Swings that were both on time and squared up — the best swing a hitter can take.
Early Timing%: Share of competitive swings where he was out in front of the pitch.
On-Time%: Share of swings timed correctly — the foundation everything else depends on.
Late Timing%: Share of competitive swings where the pitch beat him.

Hitter vs pitch-type matchups

xwOBA vs Pitch: His deserved production against one specific pitch type.
Run Value/100 vs Pitch: Runs he creates (or loses) per 100 pitches of one type he sees.

Plate discipline

Chase%: How often he swings at pitches outside the strike zone — the core discipline stat.
Whiff%: Swings that miss, as a share of all swings.
Zone Contact%: Contact rate on pitches inside the zone — bat-to-ball skill on hittable pitches.
CSW%: Called strikes plus whiffs per pitch — the cleanest single measure of pitch quality.
K%: Strikeouts per plate appearance.
BB%: Walks per plate appearance.

Speed & baserunning

Sprint Speed: Feet per second at full sprint. 27 is average; 30 is elite.

Pitch characteristics

Velocity: Average velocity for a given pitch type.
Spin Rate: Average spin rate for a given pitch — more spin generally means more movement.
Induced Vertical Break: Induced vertical break: how much the pitch resists gravity versus a spinless ball. High IVB fastballs 'rise.'
Horizontal Break: Horizontal break — arm-side or glove-side movement in inches.
Arm Angle: The arm slot at release, in degrees — 90 is straight over the top, 0 is sidearm.