xwOBA versus batting average: two different stories

A hitter is batting .250, but some nights that number seems to tell you very little. Four singles and four home runs would both add four hits. The scoreboard could look quite different.

Batting average keeps one clear job: hits divided by at-bats. Ten hits in 40 at-bats is .250. Every hit counts once, whether the hitter stops at first or circles all four bases.

Walks don't add hits or at-bats. Strikeouts do add at-bats. A batter with ten hits in 40 at-bats and ten walks still has a .250 average. Those walks help the offense, but this particular number doesn't measure them.

Use average when your question is how often the hitter recorded a hit per at-bat. Add other information when your question gets broader.

Imagine Oak and Elm each collect ten hits in 40 at-bats. Oak hits ten singles. Elm hits six singles, two doubles and two homers. They both bat .250.

Count the bases from those hits. Oak has ten. Elm has six from singles, four from doubles and eight from homers: 18 total bases. Batting average stays the same while the hit mix changes.

This doesn't calculate either hitter's xwOBA. We'd need the contact information and other included outcomes. It shows why counting hits alone leaves part of hitting out.

Picture a line drive hit straight at the center fielder. It's caught. Later, a gentle grounder rolls through a gap for a single. Batting average records the actual results: an out and a hit.

Expected statistics use the ball's speed and angle off the bat to judge what similar contact tends to produce. Running speed also enters some types of contact. A caught ball can carry more expected value than a weak hit.

Full xwOBA includes walks, hit-by-pitches and strikeouts too. It gives different outcomes different values: a home run contributes more than a single. Its full name is expected weighted on-base average.

Don't subtract .250 batting average from .350 xwOBA and call the difference missed hits. They answer different questions on different scales.

For a hit-focused comparison, AVG and expected batting average, called xBA, are the closer pair. For broader offensive value, compare wOBA and xwOBA. Both figures should use the same dates and sample.

Read whether the expected number covers all included plate appearances or only tracked batted balls. A contact-only figure leaves out plate appearances that never produced contact, including strikeouts.

Name the question first. “How often did hits happen?” points to AVG. “What did the contact and other outcomes suggest?” points to xwOBA. You can use both without forcing one decimal to explain the other.

For Oak and Elm, the useful conclusion is simple: equal hit frequency didn't mean equal extra-base production. Find the next relevant detail rather than treating xwOBA as a hit chance.