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Expected Slugging (xSLG)

What a hitter's SLG should be based on Statcast exit velocity and launch angle data.

Full Definition

Expected Slugging (xSLG) uses the exit velocity and launch angle of every batted ball to calculate what a hitter's slugging percentage 'should' be based on historical outcomes for similar contact. It strips out fielding, ballpark effects, and luck. When xSLG is significantly higher than actual SLG, the hitter has been unlucky and is due for more extra-base hits and home runs — making the xSLG gap one of the most actionable metrics for home run prop betting.

What's a good Expected Slugging?

Above .550 is elite power expected, .450-.550 is above average, .350-.450 is average, below .350 is below average.

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Related terms

Barrel Rate

Percentage of batted balls with ideal exit velocity and launch angle for extra-base hits.

Hard Hit Rate (Hard Hit%)

Percentage of batted balls with exit velocity of 95+ mph.

Slugging Percentage (SLG)

Total bases divided by at-bats. Measures power output per at-bat.

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