Metrics

Understanding the Metrics

The ACC Baseball Explorer uses modern sabermetric statistics to evaluate player performance beyond traditional statistics such as batting average, RBI, and ERA.

These metrics provide additional context by accounting for league environment, offensive value, and outcomes that are more directly controlled by the player.

Batting

wOBA

Weighted On-Base Average measures a hitter’s total offensive value per plate appearance by assigning specific run values to events like walks, singles, doubles, triples, and home runs.

\[ wOBA = \frac{0.69*BB + 0.72*HBP + 0.89*1B + 1.27*2B + 1.62*3B + 2.10* HR}{AB + BB + HBP + SF} \] where:

  • BB = Bases on Balls/Walks
  • HBP = Times Hit by a Pitch
  • 1B = Singles hit
  • 2B = Doubles hit
  • 3B = Triples hit
  • HR = Home Runs hit
  • AB = At Bats
  • SF = Sacrifice Flies

wRC+

Weighted Runs Created Plus measures a batter’s total offensive value and run creation per plate appearance, adjusted for league run environments.

\[ wRC+ = \left(\frac{wOBA - wOBA_{league}}{scale} + 1 \right) * 100 \] where:

  • wOBAleague = league-average wOBA calculated from all player plate appearances during the season
  • scale = wOBA scale factor used to normalize differences in offensive value (1.25)

Interpretation

  • 100 = league average
  • 120 = 20% above league average
  • 80 = 20% below league average

Higher values indicate stronger offensive performance.

ISO

Isolated Power measures a batter’s raw power by calculating how many extra-base hits they average per at-bat.

\[ SLG - BA \] where:

  • SLG = Slugging Percentage
  • **BA* = Batting Average

BABIP

Batting Average on Balls in Play measures how often a batted ball becomes a hit while excluding home runs and strikeouts.

\[ BABIP = \frac{H - HR}{AB - SO - HR + SF} \] where:

  • H = Hits
  • HR = Home Runs hit
  • AB = At Bats
  • SO = Strikeouts
  • SF = Sacrifice Flies

Pitching

K-BB%

K-BB% measures a pitcher’s control by subtracting total walks (BB) from total strikeouts (SO).

\[ K-BB% = K% - BB% \] where:

-K% = Strikeouts divided by batters faced -BB% = Bases on Balls/Walks divided by batters faced

FIP

Fielding Independent Pitching measures a pitcher’s true performance by focusing only on the events a pitcher has the most control over.

\[ FIP = \frac{13*HR + 3*(BB + HBP) - 2*SO}{IP} + 3.10 \] where:

  • HR = Home Runs allowed
  • BB = Bases on Balls/Walks
  • HBP = Times Hit by a Pitch
  • SO = Strikeouts
  • IP = Innings Pitched

3.10 is used as a constant to approximate a standard Earned Run Average (ERA) scale.

Interpretation

Lower FIP values indicate better pitching performance.

All metrics are calculated using the accbaseballr R package developed for ACC baseball analysis.