I am always looking at ways to make complex formulas simpler. For pitchers, I started using just K/9 minus BB/9 to measure how good they were. It has not been a bad to evaluate pitchers from one season to the next, but I haven't been able to take into account any batted balls. I really wanted to include ground ball rate since it prevents home runs and correlates decent from year to year as seen from this information from "Baseball: Between the Numbers":
Winning percentage - .204
Batting average on balls in play (BABIP) - .272
ERA - .380
Home runs per batter faced - .470
Hits allowed per batter faced - .499
Walks (W) per batter faced - .676
Strikeouts (SO) per batter faced - .790
Ground ball (GB) percentage - .807
Using the numbers that are somewhat easy to find and correlate easy from season to season, I came up with the following formula:
Jeff's secret pitching sauce = K/9 – BB/9 + [(Ground ball Percentage in Decimal format)*10]
The values doesn't represent any existing number, but correlates decent with FIPs (r-squared = -0.67) and xFIPs (r-squared = 0.91) when looking at all the qualified starters over the past 5 years.
Here is a list of how often values showed up for the starters I looked at:
|Sauce||Percent of Qualified Starters|
An equation that could be used to compare it to ERA is the following:
ERAs = -0.31*(sauce) + 6.78
I used the equation recently to look at some minor league pitchers over at RoyalsReview.com.
I never expect it to catch on, but it is an easy number to figure in your head given the 3 values. Also, It should be relatively constant from season to season. Let me know what you think.