From: drw3l@delmarva.evsc.Virginia.EDU (David Robert Walker)
Newsgroups: rec.sport.baseball
Subject: Re: The Lies Of E.R.A. With Small Samples
Date: 20 Nov 92 19:10:59 GMT
Distribution: na
Organization: University of Virginia

In article <Bxzr29.9qu@cs.dal.ca> niguma@ug.cs.dal.ca (Gordon Niguma) writes:
>  Usually E.R.A. will somehow correlate with the performance of a pitcher     
>allowing hits per 9, bb per9ip etc. However, sometimes in small 40 to perhaps
>as high as 80 innings pitched, pitchers will drastically differ in what their
>ERA is. Take the following sample (I prorated one guy from 41 2/3 innings
>to twice that amount):
>
>            IP  H  BB  SO  2B  3B  HR  H/9  BB/9  K/9  SB-CS  BA  OBA  SLG
>PITCHER A   83 74  38  62   8  0   10  8.0  4.1   6.7   10-4 236  316  357
>PITCHER B   88 80  27  47   8  1    8  8.2  2.8   4.8    2-4 249  314  355

What Gord is doing is very similar to something I did in late
September, contrasting Jack McDowell and Kirk McCaskill. Those numbers
were over even higher innings, and showed that Kirk had the better OPS
numbers, but Jack had the better ERA and Win Pct. I agree with
everything so far.

Here, he is comparing Tim Fortugno to Steve Olin, so I will replace
the remaining As and Bs.

>Yet in the ERA category we see that Fortugno registered a 5.18 ERA while
>Olin filled in at 2.34 ERA. Subtracting the ERA from the statistical
>picture probably makes Fortugno the better, more powerful pitcher, someone
>you'd rather close with or at least making it a very close decision.
>  But as we speak Fortugno is trying to hang on to a major league job while
>Olin is the closer for another team (Both American League). Anyone
>hazard a guess to who they are?
>  How can this happen? Well, these are reliever ERA's so we know that often
>the inherited runners that a pitcher allows in will not affect his ERA.
>Olin came in with 60 IR while stranding 49 of them. Fortugno had  
>only 16 (prorated) IR while stranding 10 of them. So clearly Olin's hits
>hurt his teammates ERA and not only his own. This is a HUGE factor but
>can it really account for a difference of almost 3.00 ER per 9ip?
>  Another factor maybe the ability of Olin to produce a groundball which
>his fielders turn to a deuce behind him. This would dramatically affect ERA's.
>Another maybe the "clutch" ability of Olin who happened (by luck or
>ability to "bear down" ie Jack Morris) to avoid that hit with a runner at
>third and save his ERA.

Another factor which is probably very important is the number of outs
when the man in question entered the game. Olin apparently entered
inmid-inning very often, with one or two outs already registered. Thus
he didn't have to get three outs to wipe the bases clean. Fortugno,
OTOH, started most of his innings, and has to get three outs before
any of his runners reach home. That will make up a lot of difference.

>Anyways, what does this imply about the data? Chances are that alot of this
>is EXTREME dumb luck; that if you run these stats through a simulator, the
>differences would very rarely by this wide. It may be dangerous to state
>but can this imply that:
>
>    a) batters, over 177 PA, be strong hitters despite poor OPS numbers by
>outstanding clutch performances and ability to avoid a double play?
>    b) vice versa?

What it demonstrates to me is the size of the error bars that should
be applied to our estimates of run creation, from RC or EQR or
whatever. Over a short enough time span, the situation is very
important to the total result.

>  I mentioned appplying the Runs Created Formula to pitchers to generate an
>expected ERA but was told that this was not effective (I think Valentine
>mentioned this point). I'm not exactly sure why this is so, is it because
>a pitcher is a factor in many consecutive batters in a row and thus their
>ability to induce a DP ball or to avoid a big inning by allowing minimal
>power, while batters since they are only 1/9 of the puzzle must consistently
>maximize their offensive strengths? What if we did try predicting team ERA
>by using the Runs Created Formula for hitters? Would their be a strong         
>correlation? Would their be pitchers who could consistently do better than
>their implied Runs Created ERA?
>  Just some things to think about.....
>
>					Gord Niguma
>					(fav player: John Olerud)
 Well, I did do an RC for the above lines, and it comes to 34 runs
expected for Olin, 19 for Fortugno. Actual runs allowed were 24 for
Fortugno, all of which were earned, and 25 for Olin, 23 earned.

So Fortugno, in 42 IP, had 5 more runs than expected from the stats;
plus 2 more that would often be unearned (typically 10%), for an
excess of 7 earned runs, which adds up to 1.51 points of ERA.

Olin gave up 9 fewer than expected, which can probably be almost
entirely explained by the mid-inning entrances I mentionned before.
Since he has a near normal number of earned runs, it comes out to a
deficit of 8 earned runs from expected, or a .82 improvement.

Olin's expected ERA was 3.16, -.82=2.34. Fortugno's expected was 3.67,
+1.51=5.18.

If the lessons of such things as the Pythagorean Run Theory apply,
Fortugno should "improve" to about 3.70 next year, assuming the raw
stats are a truer measure of his ability than the runs which actually
scored. He was, in a word, unlucky. Olin was not all that lucky; given
the situations he was in, an advantage of at least half a run was
likely.

There is no reason I know of, but I will readily listen to
suggestions, that the analysis shouldn't be just as useful for
pitchers as for hitters. And because the actual runs that resulted are
known, there is the ability to demonstrate that certain players are
better than their stats suggest. This would be very constructive.

Clay D.
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