Stats Glossary

Hits divided by at-bats. A .300 average is excellent, .250 is roughly league average.

How often a batter reaches base (hits + walks + HBP). More valuable than AVG because walks count.

Total bases divided by at-bats. Measures power — extra-base hits are worth more.

OBP + SLG combined. Quick shorthand for overall offensive production. .800+ is good, .900+ is excellent.

Like OBP but weights each outcome (single, double, HR, walk) by its actual run value. More accurate than OPS. Used in NUT Score calculation for hitters.

Measures offensive output adjusted for park and league. 100 is average, 120+ is great, 150+ is elite.

Self-explanatory. Total home runs hit.

Runs scored as a direct result of a batter's at-bat.

Total runs scored by the player.

Times the batter reached base safely on a ball he hit, without an error or a fielder's choice. Singles, doubles, triples and home runs all count as hits.

Hits where the batter reaches second base.

Hits where the batter reaches third base.

Times the batter reached first base on four balls.

Times the batter struck out: three strikes, swinging or called. Box scores write it SO; scorecards and most fans write K.

The scorekeeper's symbol for a strikeout, the same stat as SO. A backward K marks a called third strike.

Times the runner took an extra base on his own, without a hit, walk, error or wild pitch helping him.

Times the runner was thrown out trying to steal a base.

Bases gained on hits: 1 for a single, 2 for a double, 3 for a triple, 4 for a home run. Slugging percentage is total bases divided by at-bats.

Runners still on base when an inning ends. In a box score it is counted for each batter and for the team; a high team LOB means missed chances to score.

Total trips to the plate, including walks, HBP, sacrifices.

Plate appearances minus walks, HBP, sacrifices, and certain other outcomes.

Times the batter was hit by a pitched ball and awarded first base.

Times the batter hit a ground ball that resulted in two outs.

SLG minus AVG. Measures raw extra-base power only. A .200+ ISO indicates strong power.

Percentage of a hitter's total pitches seen that result in a swing-and-miss. The hitter equivalent of Whiff% — lower means better contact ability.

Percentage of a hitter's swings that result in contact (foul or in play). A direct measure of bat-to-ball skill — higher is better.

Percentage of pitches a hitter swings at, regardless of zone. Stylistic rather than directional — patient hitters and aggressive ones can both succeed.

Average number of pitches a hitter sees each plate appearance. Higher means seeing more pitches and working deeper counts. League average is about 3.9.

Earned runs allowed per 9 innings. Lower is better. Under 3.00 is excellent.

Like ERA but only counts what the pitcher controls: strikeouts, walks, HBP, and home runs. Strips out defense and batted-ball variance. Used in NUT Score calculation for pitchers.

How many baserunners a pitcher allows per inning. Under 1.10 is great.

Total innings thrown.

Pitcher wins. Widely considered misleading since wins depend heavily on run support.

Pitcher losses. Same caveat as wins.

Games finished in a save situation by a reliever.

Total batters struck out.

Total walks issued.

Strikeout rate normalized to 9 innings.

Walk rate normalized to 9 innings.

Home run rate.

Opponents' batting average against the pitcher: hits allowed divided by at-bats against. Lower is better; league average is around .245.

Hits a pitcher gave up. Box scores usually list it as H in the pitching lines.

Number of games where the pitcher started on the mound.

A start of at least 6 innings with 3 or fewer earned runs allowed.

A relief appearance where the pitcher enters in a save situation, records at least one out, and leaves without giving up the lead.

Percentage of plate appearances that end in a strikeout. More reliable than K/9 because it accounts for baserunners.

Percentage of plate appearances that end in a walk. Lower is better for pitchers, higher is better for hitters.

Strikeouts divided by walks. A pitcher at 3.0 or higher strikes out three batters for every one he walks, which is good; 5.0+ is elite.

K% minus BB%. The single best one-number measure of pitcher skill — combines bat-missing ability with command. More predictive than K% alone.

Percentage of baserunners a pitcher strands without scoring. League average is around 73%. Extreme highs or lows often signal luck that will regress.

Percentage of swings against a pitcher that miss entirely. Higher means more bat-missing stuff. The pitcher's perspective on swing-and-miss.

Percentage of a pitcher's pitches that are strikes (called or swung at). A measure of how often a pitcher fills the zone or generates chases.

Total player value in wins above a replacement-level player. Two main versions: bWAR (Baseball Reference) and fWAR (FanGraphs). They often disagree because they use different defensive models. NUT was created as a simpler alternative that excludes defense.

Baseball Reference's version of WAR. Includes defense using DRS (Defensive Runs Saved).

FanGraphs' version of WAR. Includes defense using UZR (Ultimate Zone Rating).

OPS adjusted for park and league factors. 100 is average. Makes it easier to compare players across eras and ballparks.

ERA adjusted for park and league. 100 is average, higher is better (opposite of raw ERA).

Batting average on batted balls excluding home runs. League average is around .300. Extremes often indicate unsustainable variance that will regress. Useful for spotting hot or cold streaks.

Predicted batting average based on exit velocity and launch angle of batted balls. Compares what a player "should" be hitting vs actual results.

Predicted slugging based on exit velocity and launch angle. Shows expected power output regardless of batted-ball luck.

Predicted wOBA based on quality of contact. The key input for xNUT — reveals whether a hitter's production is backed by real contact quality or luck.

Predicted ERA based on the quality of contact a pitcher allowed. Complements FIP by measuring how well a pitcher suppresses hard contact.

Like FIP, but swaps a pitcher's actual home runs for a league-average rate on fly balls. Strips out home-run luck to show the skill underneath — often a better predictor of future ERA than FIP or ERA.

How hard the ball comes off the bat in mph. The most fundamental measure of contact quality — harder contact means more hits and more extra-base hits.

The vertical angle the ball leaves the bat in degrees. Combined with exit velocity, determines whether a batted ball becomes a hit, homer, or out.

Percentage of batted balls hit at the ideal combination of exit velocity (98+ mph) and launch angle for extra-base hits. Higher means more damage on contact.

Percentage of batted balls with exit velocity of 95+ mph. A broader measure of contact quality than barrel rate — higher means more damage on contact overall.

Estimates runs saved or cost by a fielder compared to average. Used in bWAR. Can be unreliable in single-season samples, which is why NUT excludes defense.

Another defensive metric, used in fWAR. Measures runs saved based on where batted balls land. Like DRS, can fluctuate significantly year to year.

A fielding metric that uses tracking data to measure how many outs a defender makes above average. More reliable than older defensive metrics but still limited.

A runner's average top speed in feet per second on his fastest competitive runs. 27 ft/s is average, 30+ is elite. A pure measure of raw foot speed.

What a player's NUT score "should" be based on expected wOBA, which uses exit velocity and launch angle to strip out batted-ball variance. For hitters, xNUT comes from xwOBA and PA; for pitchers, it comes from xwOBA-against and total batters faced. If actual NUT is much higher than xNUT, the player may be overperforming. If lower, they're underperforming and due for positive regression.

A pitcher's NUT calculated from actual ERA instead of FIP. Comparing ERA NUT to regular (FIP-based) NUT reveals whether a pitcher's results match their skill indicators. If ERA NUT is higher than NUT, the pitcher is overperforming their underlying metrics.

A measure of how much a ballpark affects scoring compared to league average. A factor of 104+ means a hitter-friendly park, 96 or below means a pitcher-friendly park. Park factors vary by venue and are updated annually.

Where a player ranks among all qualified MLB players for a given stat, expressed as 0-100. A 90th percentile in HR means the player has more home runs than 90% of qualified players.

MLB's challenge system for ball and strike calls (introduced 2026). Players can challenge an umpire's call, and the ABS system uses Hawk-Eye tracking to determine if the pitch was in the zone. Baseball NUT tracks challenge results by team on every team page and the Stats leaderboard.