Walks plus Hits per Inning Pitched = (BB + H) / IP
ERA
Earned Run Average (using 4 innings as standard game length) = 4 * (ER / IP)
FIP
Fielding Independent Pitching measures how well a pitcher pitched independent of his team's defense by taking into account home run, walk, and strikeout rates.
More details about the exact FIP formula used is available.
xFIP
Expected Fielding Independent Pitching is the same as FIP except, instead of using raw home run rate, the league-average HR/F is used to estimate how many home runs the pitcher should have allowed (the assumption being that some part of home runs given up is purely luck).
TTO%
Three True Outcomes Percentage is the percentage of plate appearances that result in one of the three defense-independent batting events: home runs, walks, and strikeouts.
RA
Run Average (using 4 innings as standard game length) = 4 * (R / IP)
K/4
Strikeouts per 4 innings pitched = 4 * (K / IP)
BB/4
Walks per 4 innings pitched = 4 * (BB / IP)
H/4
Hits per 4 innings pitched = 4 * (H / IP)
K/BB
Strikeouts per Walk = K / BB
CRA
Contact Rate Against = (AB - K) / AB
BAA
Batting Average Against = H / (H + Outs)
BABIP
Batting Average on Balls In Play = [H - HR] / [AB - K - HR + SF]. BABIP is mostly an indicator of the pitcher's defense. A relatively high BABIP indicates a poor defense.
LOB%
Left On Base Percentage is the percentage of baserunners allowed that did not score a run.
SLGA
Slugging percentage Against = TB / AB
ISOA
Isolated Power Against estimates hitters' raw power against a pitcher. The PECOTA formula, which weights doubles and triples evenly ([2B + 3B + (3 * HR)] / AB), is not used here because only doubles and triples are a poor indicator of power in wiffleball. [(3 * HR) / AB] is used here instead.
Go/Fo
Ground ball to fly ball ratio is: Groundouts / Flyouts.
Runners on Base is the total number of runners on base at the time the batter's plate appearances began.
CR
Contact Rate = (AB - K) / AB
BA
Batting Average = H / AB
BABIP
Batting Average on Balls In Play = [H - HR] / [AB - K - HR + SF]. BABIP is indication of how well a hitter places the ball combined with their speed.
BACON
Batting Average on Contact = H / [AB - K + SF]. BACON is BABIP but with home runs included.
SPD
Speed Score attempts to measure speed using a combination of doubles, triples and runs scored other than by home runs.
RS%
Runs Scoring Percentage is the percentage of times that a baserunner scored a run. (R - HR) / (H + BB - HR)
OBP
On-base Percentage = (H + BB) / (AB + BB + SF)
SLG
Slugging Percentage = TB / AB
OPS
On-base Plus Slugging = OBP + SLG
ISO
Isolated Power estimates a hitters raw power. The PECOTA formula, which weights doubles and triples evenly ([2B + 3B + (3 * HR)] / AB), is not used here because only doubles and triples are a poor indicator of power in wiffleball. [(3 * HR) / AB] is used here instead.
SecA
Secondary Average is a ratio of bases gained to at bats using the formula: (TB - H + BB) / AB.
Weighted Runs Above Average per Plate Appearance measures the average number of runs a player contributed to their team in a single plate appearance compared to the average player.
wRAA
Weighted Runs Above Average measures the total number of runs a player contributed to their team compared to the average player.
wRC/PA
Weighted Runs Created per Plate Appearance measures the average number of runs a player contributed to their team in a single plate appearance.
wRC
Weighted Runs Created measures the total number of runs a player contributed to their team.
TTO%
Three True Outcomes Percentage is the percentage of plate appearances that result in one of the three defense-independent batting events: home runs, walks, and strikeouts.
OBI%
Others Batted In Percentage is a measure of a hitter's performance with runners on base. It is the percentage of runners that the hitter caused to score (not including themselves via Home Runs) compared to the runners that were on base for the hitter. The formula is: (RBI - HR) / ROB.
Go/Fo
Ground ball to fly ball ratio is: Groundouts / Flyouts.
Walks plus Hits per Inning Pitched = (BB + H) / IP
ERA
Earned Run Average (using 4 innings as standard game length) = 4 * (ER / IP)
FIP
Fielding Independent Pitching measures how well a pitcher pitched independent of his team's defense by taking into account home run, walk, and strikeout rates.
More details about the exact FIP formula used is available.
xFIP
Expected Fielding Independent Pitching is the same as FIP except, instead of using raw home run rate, the league-average HR/F is used to estimate how many home runs the pitcher should have allowed (the assumption being that some part of home runs given up is purely luck).
TTO%
Three True Outcomes Percentage is the percentage of plate appearances that result in one of the three defense-independent batting events: home runs, walks, and strikeouts.
RA
Run Average (using 4 innings as standard game length) = 4 * (R / IP)
K/4
Strikeouts per 4 innings pitched = 4 * (K / IP)
BB/4
Walks per 4 innings pitched = 4 * (BB / IP)
H/4
Hits per 4 innings pitched = 4 * (H / IP)
K/BB
Strikeouts per Walk = K / BB
CRA
Contact Rate Against = (AB - K) / AB
BAA
Batting Average Against = H / (H + Outs)
BABIP
Batting Average on Balls In Play = [H - HR] / [AB - K - HR + SF]. BABIP is mostly an indicator of the pitcher's defense. A relatively high BABIP indicates a poor defense.
LOB%
Left On Base Percentage is the percentage of baserunners allowed that did not score a run.
SLGA
Slugging percentage Against = TB / AB
ISOA
Isolated Power Against estimates hitters' raw power against a pitcher. The PECOTA formula, which weights doubles and triples evenly ([2B + 3B + (3 * HR)] / AB), is not used here because only doubles and triples are a poor indicator of power in wiffleball. [(3 * HR) / AB] is used here instead.
Go/Fo
Ground ball to fly ball ratio is: Groundouts / Flyouts.
Runners on Base is the total number of runners on base at the time the batter's plate appearances began.
CR
Contact Rate = (AB - K) / AB
BA
Batting Average = H / AB
BABIP
Batting Average on Balls In Play = [H - HR] / [AB - K - HR + SF]. BABIP is indication of how well a hitter places the ball combined with their speed.
BACON
Batting Average on Contact = H / [AB - K + SF]. BACON is BABIP but with home runs included.
SPD
Speed Score attempts to measure speed using a combination of doubles, triples and runs scored other than by home runs.
RS%
Runs Scoring Percentage is the percentage of times that a baserunner scored a run. (R - HR) / (H + BB - HR)
OBP
On-base Percentage = (H + BB) / (AB + BB + SF)
SLG
Slugging Percentage = TB / AB
OPS
On-base Plus Slugging = OBP + SLG
ISO
Isolated Power estimates a hitters raw power. The PECOTA formula, which weights doubles and triples evenly ([2B + 3B + (3 * HR)] / AB), is not used here because only doubles and triples are a poor indicator of power in wiffleball. [(3 * HR) / AB] is used here instead.
SecA
Secondary Average is a ratio of bases gained to at bats using the formula: (TB - H + BB) / AB.
Weighted Runs Above Average per Plate Appearance measures the average number of runs a player contributed to their team in a single plate appearance compared to the average player.
wRAA
Weighted Runs Above Average measures the total number of runs a player contributed to their team compared to the average player.
wRC/PA
Weighted Runs Created per Plate Appearance measures the average number of runs a player contributed to their team in a single plate appearance.
wRC
Weighted Runs Created measures the total number of runs a player contributed to their team.
TTO%
Three True Outcomes Percentage is the percentage of plate appearances that result in one of the three defense-independent batting events: home runs, walks, and strikeouts.
OBI%
Others Batted In Percentage is a measure of a hitter's performance with runners on base. It is the percentage of runners that the hitter caused to score (not including themselves via Home Runs) compared to the runners that were on base for the hitter. The formula is: (RBI - HR) / ROB.
Go/Fo
Ground ball to fly ball ratio is: Groundouts / Flyouts.