In baseball statistics

Baseball statistics

Statistics play an important role in summarizing baseball performance and evaluating players in the sport.Since the flow of a baseball game has natural breaks to it, and normally players act individually rather than performing in clusters, the sport lends itself to easy record-keeping and statistics...

,
Defense-Independent ERA (dERA), created by Voros McCracken

Voros McCracken

Robert "Vörös" McCracken is a prominent sabermetrician. Vörös is a nickname from his Hungarian heritage, meaning "red," specifically "blood red." He is most widely recognized for his pioneering work on Defense Independent Pitching Statistics .-DIPS published:McCracken first publicly disclosed his...

, projects what a pitcher's earned run average

Earned run average

In baseball statistics, earned run average is the mean of earned runs given up by a pitcher per nine innings pitched. It is determined by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine...

 (ERA) would have been, if not for the effects of defense and luck on the actual games in which he pitched.

Method

Version 2.0 of dERA uses the following statistics:

• Batters Faced (BFP)
• Home Runs Allowed (HR)
  Home runs allowed
  In baseball statistics, home runs allowed signifies the total number of home runs a pitcher allowed.The record for the most home runs allowed by any pitcher belongs to Jamie Moyer , the oldest active pitcher in the major leagues...
  
  
• Total Walks Allowed (BB)
  Base on balls
  A base on balls is credited to a batter and against a pitcher in baseball statistics when a batter receives four pitches that the umpire calls balls. It is better known as a walk. The base on balls is defined in Section 2.00 of baseball's Official Rules, and further detail is given in 6.08...
  
  
• Intentional Walks Allowed (IBB)
  Intentional base on balls
  In baseball, an intentional base on balls, usually referred to as an intentional walk and denoted in baseball scorekeeping by IBB, is a walk issued to a batter by a pitcher with the intent of removing the batter's opportunity to swing at the pitched ball...
  
  
• Strikeouts (K)
  Strikeout
  In baseball or softball, a strikeout or strike-out occurs when a batter receives three strikes during his time at bat. A strikeout is a statistic recorded for both pitchers and batters....
  
  
• Hit Batsmen (HB)
  Hit by pitch
  In baseball, hit by pitch , or hit batsman , is a batter or his equipment being hit in some part of his body by a pitch from the pitcher.-Official rule:...
  
  

0) Multiply BFP by 0.0074 to get the number of intentional walks allowed (dIBB).

1) Divide HB by BFP-IBB. Call this $HB. Then multiply $HB by BFP-dIBB. This number gives the DIPS number of Hit Batsmen (dHB).

2) Divide (BB-IBB) by (BFP-IBB-HB), and call this number $BB. Multiply BFP by 0.0074, and call this dIBB.

2a) Then multiply $BB by (BFP-dIBB-dHB). Take this number and add IBB. This number is now the DIPS number of total walks allowed (dBB).

3) Divide K by (BFP-HB-BB) and call this number $K. Remember this number for later.

3a) Multiply $K by (BFP-dBB-dHB). This gives the DIPS number of strikeouts (dK).

4) Divide HR by (BFP-HB-BB-K) and call this number $HR. Remember this number for later.

4a) Multiply $HR by (BFP-dBB-dHB-dK). This gives the DIPS number of Home Runs (dHR).

5) Calculate the number of 'Balls Hit in the Field of Play'. This is BFP-dHR-dBB-dK-dHB.

6) Estimate hits per balls in the field of play ($H):

6a) Take the number 0.304396 and subtract 0.010830 if the pitcher is strictly a knuckleball pitcher. If not keep the 0.304396 number.

6b) Take the result from the last step and add 0.002321 if the pitcher is left-handed, if not keep the number from the above step.

6c) Take the $K figure from above and multiply it by 0.04782. Subtract this number from the number in 6b.

6d) Take the $HR figure from way above and multiply it by 0.08095. Subtract this number from the number in 6c.

6e) Whatever remains is the $H figure.

7) To get the projected number of Hits Allowed (DIPS 'Hits Allowed', or dH), multiply $H by the number of balls hit in the field of play (BHFP).

7a) Add this number to dHR. This number is the DIPS total of Hits Allowed (dH).

8) Take BFP-dBB-dHB-dK-dH and multiply that number by 1.048. Add dK to that number. Take that number and divide by 3. This is the DIPS total of Innings Pitched (dIP).

9) Sum the following products:

(dH-dHR)*0.49674

dHR*1.294375

(dBB-dIBB)*0.3325

dIBB*0.0864336

dK*(-0.084691)

dHB*0.3077

(BFP-dHB-dBB-dK-dH)*(-0.082927)

The sum of all of these is the DIPS total of earned runs (dER).

10) Calculate ERA as usual: (9*dER)/dIP. This is the DIPS ERA (dERA).

Alternative formulation

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See also

• Earned run
  Earned run
  In baseball, an earned run is any run for which the pitcher is held accountable . Any runner who tags his base and reaches home plate is scored against the pitcher as an earned run...
  
  
• Earned run average
  Earned run average
  In baseball statistics, earned run average is the mean of earned runs given up by a pitcher per nine innings pitched. It is determined by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine...
  
  
• Component ERA
  Component ERA
  Component ERA or ERC is a baseball statistic invented by Bill James. It attempts to forecast a pitcher's earned run average from the number of hits and walks allowed rather than the standard formula of average number of earned runs per nine innings...
  
  
• PERA
  Peripheral ERA
  Peripheral ERA is a pitching statistic created by the Baseball Prospectus team. It is the expected earned run average taking into account park-adjusted hits, walks, strikeouts, and home runs allowed. Unlike Voros McCracken's DIPS, hits allowed are included...
  
  
• QERA