Jeff's Special Sauce - Easy Formula for Evaluating Pitchers

by Jeff Zimmerman on Aug 11, 2010 12:42 AM EDT

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
12	0.7%
11	6.2%
10	10.2%
9	15.6%
8	18.5%
7	22.5%
6	18.2%
5	6.4%
4	1.7%

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.

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Comments

instead of k/9 or bb/9 why k% and bb% since as we know not all Innings pitched are created equal

by Alexander אלכסנדר Mermelstein on Aug 11, 2010 2:59 AM EDT reply actions

The values are readily available at various websites.

Most only have K/9 or BB/9

I bet the numbers may be just as close though

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by Jeff Zimmerman on Aug 11, 2010 7:53 AM EDT up reply actions

If you're using it for minor leaguers

You can get K and BB%‘s from FirstInning.com or they’re easy enough to calculate.

My old blog is Tigers By The Numbers.

Now I write at Bless You Boys.

Like music? See what I'm listening to at my Last.fm account.

by Mike Rogers on Aug 11, 2010 3:04 PM EDT up reply actions

It doesn't really matter because that will inflate or deflate both K/9 and BB/9

by vivaelpujols on Aug 12, 2010 4:26 AM EDT up reply actions

I like it as a do-it-in-your-head number.

7-8 is average, 9-10 is good, 11-12 is outstanding. Easy enough if you’re at a site that doesn’t have xFIP but does have GB%.

I don’t think I’d use it for any sort of real study, but you’re probably not pitching it as that, right?
-j

I write at:
Beyond the Boxscore | Red Reporter | Basement-Dwellers.com | Twitter: @jinazreds

by JinAZ on Aug 11, 2010 8:30 AM EDT reply actions

It would stand up in a real study, but really like it for minor league numbers

I don’t have the time/brain storage to know all the league and park factors for the minors. If the player doesn’t have good numbers against minor league hitters, his numbers will only get worse in the majors.

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by Jeff Zimmerman on Aug 11, 2010 8:39 AM EDT up reply actions

bbFIP

You should compare it to batted ball FIP.

If you are touting it as a shortcut, then you should show its limits. Two issues is IP instead of PA, and GB per BIP as opposed to GB-FB per PA.

by tangotiger on Aug 11, 2010 8:41 AM EDT reply actions

Good idea Tom.

I was just trying keep it simple with readily available information. In most cases I still just use the K/9 – BB/9 numbers and just add 4 to it for a basic/average ground ball rate.

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by Jeff Zimmerman on Aug 11, 2010 9:34 AM EDT up reply actions