Hopkins Millers

The classic measure of how often a batter gets a hit per at bat. Simple and widely understood, though it treats all hits equally and ignores walks.

Measures how often a batter reaches base by any means. Strongly correlated with run scoring — the most important job of a hitter is to not make outs.

Weights hits by their extra-base value (1B=1, 2B=2, 3B=3, HR=4). Captures power output that AVG ignores.

Combines getting on base and hitting for power into one number. A reliable single-number offensive summary that correlates well with run production.

A walk has the same value as a single for reaching base. A high walk rate signals a disciplined hitter who is hard to get out.

Strikeouts are the least productive out — no chance of advancement, error, or sacrifice. Lower K rates generally indicate better bat control.

Counts all hits that advance the batter past first base. A simple tally of power contact events.

The raw base-advancement engine behind SLG. Useful for comparing raw power output across hitters.

Measures how often batted balls (excluding HR and K) become hits. League-average BABIP is typically around .300. Sustained deviation up or down often signals luck — useful for identifying hitters who may be over- or under-performing.

Measures baserunning aggression and speed. Value depends on success rate — a low success rate can cost more bases than are gained.

Strips out singles to measure pure extra-base power. A hitter with .200 SLG and .200 AVG has zero ISO — all their hits are singles. Higher ISO = more doubles, triples, and home runs per at bat.

Like OPS but gives OBP 50% more weight, reflecting research that reaching base is more valuable than extra bases. More accurately predicts run contribution than raw OPS.

Bill James's formula estimating how many runs a player produces based on their ability to reach base and advance runners. Scales naturally with plate appearances.

Rewards process over result. A player who fights off tough pitches and works counts is contributing even on outs. High QAB% players put pressure on opposing pitchers.

Normalizes walk frequency per plate appearance regardless of lineup construction. More stable than raw BB counts and a cleaner indicator of plate discipline than BB/K.

Measures how often a batter misses when they swing. High whiff rates indicate vulnerability to strikeouts and difficulty making contact in hitter's counts. Lower is better.

Leadoff PAs are high-value situations — getting on base with nobody out sets up scoring chances. This isolates plate appearances where the stakes for reaching base are highest.

Filters to the plate appearances that most directly affect game outcomes — close-and-late situations with runners on. Separates hitters who perform under pressure from those who pad numbers in lopsided games.

Measures how deep into counts a batter works. Higher PS/PA tires out pitchers faster, exposes the bullpen earlier, and gives teammates a longer look at the pitcher's stuff.

The subset of PS/PA that counts plate appearances reaching at least 6 pitches. Long at bats are disproportionately tiring for pitchers and force mistake pitches.