From: steph@pegasus.cs.uiuc.edu (Dale Stephenson)
Subject: Re: defensive measures of performance (was -- Re: Lists: The Best Players In Baseeball)
Keywords: RF, DA, ???
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Distribution: na
Date: Sat, 9 Jan 1993 03:41:28 GMT

In <1993Jan8.205929.9120@athena.mit.edu> cmk@athena.mit.edu (Charles M Kozierok) writes:

>In article <steph.726521280@pegasus.cs.uiuc.edu> steph@pegasus.cs.uiuc.edu (Dale Stephenson) writes:
>>In <1993Jan8.032738.23621@athena.mit.edu> cmk@athena.mit.edu (Charles M Kozierok) writes:
>>>based on your comments, and the post by Clay where he explains
>>>what the DA and RF are (thanks, btw), i would have to conclude that
>>>these statistics definitely are bogus. i don't know why anyone would
>>>use them to judge much of anything. i know i wouldn't.
>>
>>Why use it?  Because, (lousy as it is) it's the best I have available to me.

>(oh boy, i can just *see* Roger Maynard drooling over this one... :^)

>all i will say is that a lousy statistic is *worse* than no statistic at all.
>i believe that should be self-evident.

It depends *how* lousy the statistic.  If it says nothing more than blind picks
would, it is a bad statistic.  If it actually runs counter to reality, it is
evil.  If it is positive, it has some value.  Kind of like this:

(If player value could be accurately measured)

            Reality     Good       Bad       Lousy, but useful     Evil
A             1          1.2        2             1.75              4
B             2          1.9        2             1.83              3
C             3          3.0        2             2.75              2
D             4          3.3        2             2.58              1

>i understand your predicament, but i personally would rather have no answer
>than the wrong one. and we have already seen at least one example where
>a player has been misjudged due to this stupidistic (tm).

Well, he would be misjudged if we used to proclaim Alomar worse than Steve
Sax.  But we were comparing Alomar to Sandberg, both of home have "gold
glove" reputations.  That Sandberg makes a lot more plays is in his favor.
It's certainly not a clinching argument -- there are too many unknown
variables.  But it is a pro-Sandberg data point.

Were we comparing Manny Lee to Jeff Blauser, I don't think anyone would
quarrel with the range factor data.  I think there are more players correctly
classified than not.

>>It's really kind of frustrating, because it less useful than having batting
>>average without OBA or SLG.  There are no end of things that can wrong with
>>range factor -- balls not being distributed evenly is only one. Another is
>>overall team defense -- even the worst defense still makes at least 24 outs per
>>9 inning game, and they've got to go somewhere.  A team with nine atrocious
>>fielders and a pitcher with 0 strikeouts would have about the same range
>>factors as a team with 9 incredible fielders.

>you score points in my book for admitting as much. seriously.

Well, the last problem has been on my mind a lot, since my computer league
Gold Glove voting goes by a mythical stat called Stolen Hits -- sort of an
error in reverse.  My program doesn't have many of the problems real range
does -- balls are fairly evenly distributed (lefty/righty makes a difference),
the turf conditions are the exact same everywhere, and the computer scorer
is never capricious.  And yet with all those variables controlled, the best
players don't always lead in Stolen Hits -- because of team defense.  In one
league I have two shortstops, both initialled SS.  Shortstop A is the superior
fielder, but Shortstop B has more stolen hits.  Shortstop A plays with the
best 2nd and 3rd basemen in the league, Shortstop B plays with two of the
worst.  Team A is teeming with great defensive players -- but they rob each
other of opportunities, costing each other gold gloves.  Shorstop B is the
only infielder capable of catching the ball, so he makes a lot of outs.

Now, this is somewhat more extreme than any real life examples would be.  But
the problem is still there.

>>So why use it all?  My alternatives would be 1) Error Totals, which is worse
>>than range, and 2) Gold glove voting. Given who does the voting, I find it
>>hard to believe that it correlates better with reality than range factors.
>>In individual cases (Alomar?) it might, but as a general rule?

>you sound like a smart guy. invent something better! start with one
>of the stupidistics and make the necessary adjustments. or start with
>a clean slate.

Can't do it with just innings, PO, A, and E.  And those are the only things
I have in my Baseball Weekly.  I would love it if they printed DA, and the
necessary stats used in calculating that.  Maybe sometime.

>>And defense *is* important, and should be talked about.  So I can't leave it
>>alone.

>then i think we should at least attach a good-sized list of caveats to
>any evaluation that uses those stats.

How 'bout this caveat : FWIW.

>>Range does have the advantage of measuring something positive the
>>player did do -- make outs.  If Alomar gets less groundballs than any other
>>AL second baseman, despite making *every play* hit his way, is his stellar
>>defense really that valuable to the Jays?

>that is actually an interesting point.

I think so, although it doesn't solve the Sandberg vs. Alomar defensive
issue.  I wonder if a factor like this should be considered in the MVP
debate?  :->

>>Shouldn't they try to put him in
>>a package for Frank Thomas and sign Jeff Treadway to play second? Now, these
>>doesn't help a great deal when comparing players.  But both Sandberg and
>>Alomar are considered fine defensive second baseman.  But Sandberg helped his
>>team more defensively, as far as I can tell.

>depends on the purpose of the comparison. some people misinterpret what the
>statistic means, and don't realize that Alomar would help his team a lot
>more than Sandberg does if Alomar was a Cub (shudder...)

>saying Alomar is less valuable to his team is fine, as long as that
>isn't projected onto Alomar himself. which has been done. that is my
>objection.

It's a valid objection.  FWIW, when the gold gloves were announced, I listed
the winners along with where they rated in the range statistic.  The NL
correlated pretty well (a lot of #2s and #3s), while the AL didn't correlate
well at all.  Weird.

>>>maybe subjective judgment actually wins out here. or maybe someone
>>>can come up with a new stat that actually makes some sense.
>>
>>Defensive Average makes sense to me.  It's going in the next revision of my
>>baseball game.

>what about park effects? how can it be of any value without park effects?
>surely you could do better than the current definition.

Actually, if we have home and road numbers, we can calculate a defensive
park adjustment, just like we do for offensive numbers.  I think it will
be relatively minor, no worse than offensive park adjustment.  If it turns
out to be huge, it should show up in the raw statistics used for DA.

Besides, for putting in my baseball game, the park effects are very minor :->.
All infields are the same, and the outfields only come in three sizes.

>>>anyone who disagrees, please explain why they do make sense. because
>>>it is clear that they ignore so many different important factors
>>>that they are essentially useless. or maybe worse, if they fool people
>>>into believing they are useful when they are not.
>>
>>You could say the same thing about RBI totals, and you'd be right :->.

>and those have been slashed and burned on this newsgroup, n'est-ce pas?

Well, yes.  But my problem with RBI totals aren't that they are *evil* (see
definition above), but that there are better tools available.  Why use RBI
totals when OBP and SLG are in every McWeekly?

>>But I believe that *if we had no better statistic available* RBI totals *would*
>>be more accurate than a random distribution in assessing worth, and most
>>likely would be more valuable than the Mediots assessment.  IMHO, of course.

>but that is why we use more intelligent stats like SLG.

>>Note that Defensive Average does not suffer from the distribution problem,
>>and therefore is much more reliable than range factor.  It still may suffer
>>from park effects, and of course distribution of "hard" chances, but I'm
>>inclined to believe those effects would be minor.

>really? how can playing on turf versus playing in the "heavy rough" in Detroit
>not have a significant effect on ground balls? i find that *very* hard to
>believe.

See above.  If there is a significant park effect, it should be measurable.
Now, I can envision problems with DA - I don't know how well they've been
answered.  If infielders really are only measured on ground balls, we're
missing how well they snag liners, go back for short flies, or turn double
plays.  First basemen's ability to make catches isn't measured.  Boundaries
cause me concerns -- what about a player making plays in someone else's
zone.  Those could be either 1) depriving the home zone player of a chance
he ordinarily would have made, or 2)  saving the home zone player from a
chance he would have missed.  An imbalance between #1 and #2 would skew
the results.  I don't have great answers myself -- but the concept of DA is
good, and gives a stastic whole worlds better than what we had to work
with.

>>I definitely have more faith in it than in subjective judgement.

>well i understand not wanting to use a subjective judgment. but DA sounds
>pretty bad, even if better than RF. your decision to use DA instead of
>subjective judgment sounds primarily like a... well... subjective judgment.

True.  That's the real purpose of subjective judgement -- to find something
better :->.

-- 
Dale J. Stephenson |*| (steph@cs.uiuc.edu) |*| Baseball fanatic

  "It is considered good to look wise, especially when not 
   overburdened with information" -- J. Golden Kimball
Newsgroups: rec.sport.baseball