Wednesday, October 17, 2007

Runs Created Average

Earlier in the year, when I first started this blog, I made a post about the stats I use to evaluate pitchers and mentioned a statistic called RCA, or Runs Created Average, I invented. I`m constantly tweaking it but I`ll try and explain its present version. First of all here's the formula:

RCA= (Average Pitcher's Runs Surrendered/9)+(Expected Runs Surrendered Above Average)/(Expected Outs Pitched/3)

Pitcher's Runs Surrendered/9 is what is commonly known as RA (Run Average). It is like ERA but counts unearned runs.

Expected Runs Surrendered Above Average (ERSAA) and Expected Outs Pitched (EOP) are statistics I invented. They are based on the GB/FB/IFFB/LD/SO/BB/HBP a pitcher has and the run value and percentage of the time they are outs of each one. The numbers these different types of events are multiplied are the run values of them (That is for ERSAA) and percentage of the time these types of event are converted into outs.

ERSAA= (SO* -.287)+(IFFB*-.243)+(GB* -.101)+(FB*0.035)+(LD*0.356)+(BB*0.315)+(HBP*0.342)

EOP= (SO*1.00)+(BB*0.00)+(HBP*0.00)+(GB*.772)+(LD*.1 88)+(FB*.812)+(IFFB*.962)

EOP is then divided by three to convert them into Innings Pitched.

Here is an example. John Smith has these statistics one year.

SO- 200

BB- 50

HBP- 5

GB- 350

FB- 120

IFFB- 10

LD- 100

Average RA- 4.80

John Smith's RCA = 4.80+(-37.92/(596.06/3) = 4.61

Why do I use this instead of other pitching statistics?

We all know the flaws of conventional statistics such as ERA, Wins, and Losses but DIPS statistics are also flawed. Studies have suggested that pitchers cannot control their HR/FB% as much as is sometimes assumed. As a result HR's are not an accurate measure of a player's ability to prevent HR's. I prefer GB% or GB's. It also includes the exact values of these different events. K/BB is a statistic I use a lot but it does not account for the fact that a player with a 200/50 SO/BB ratio in 200 IP is better than a pitcher that has a 100/25 SO/BB ratio in 200 IP. One walk does not fully offset a strikeout. Using LD% also accounts for part of a pitcher's control in keeping a low BABIP. A big inspiration for my work here was a post on a Mariners blog I stumbled upon about evaluating pitchers.

If you have any comments or questions please post them in the comments section.

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