From: dtate+@pitt.edu (David M Tate)
Newsgroups: rec.sport.baseball
Subject: Re: Value of Stats
Date: 28 Jul 92 21:02:41 GMT
Organization: Factors of Ys, Inc.

In article <1992Jul28.192601.10342@ramsey.cs.laurentian.ca> 91287041@ramsey.cs.laurentian.ca (roger maynard) writes:
>In <3832@blue.cis.pitt.edu.UUCP> dtate+@pitt.edu (David M Tate) writes:
>
>>>>       Bonds:          48.6 + 5.1 = 53.7 marginal runs
>>>>       Puckett:        25.2 + 0.3 = 25.5 marginal runs
>>>>       Salazar:         4.5 - 1.8 =  2.7 marginal runs
>
>>What possible relevance is there in what fraction of the team's
>>production this represents?  That's information about how good Bonds's team-
>>mates were, not about Bonds himself.
>
>It would tell us what percentage of a division-winning offence Bonds is
>repsonsible for.  Likewise Puckett.  

Yes, it would, by definition.  But who cares about the *percentage*?  That's
what I don't understand.  It's an interesting curiosity that Bonds did or did
not personally account for X% of the Pirates' offense, but I don't see how it
has any relevance to deciding how good Bonds is/was.  "Value" doesn't accrue
in units of "% team runs"; it accrues in units of "wins", through runs added
and subtracted from what the team would have scored.

>It would tell us who carried the 
>biggest load, that is, it could be a measure of MVP.  

But loads are absolute, not relative.  If you carry 82 pounds for a mile, and
I carry 71 pounds for a mile, you carried the greater load, regardless of the
fact that my 71 pounds was 47% of my team's load, while your 82 pounds was
only 22% of your team's load.

>>How can you get a measure of individual value by dividing by what a bunch of
>>other people did?  All that would tell you is how much better than the rest of
>>the team these guys are, using your definition of 'better'.  Or, equivalently,
>>how much worse than these guys the rest of the team was.
>
>Yes but if we are talking about the "best" teams it might be interesting to
>see how large the individual contributions were to the winning effort.

We know how large they were.  About 54 runs, compared to about 26 runs.

You can't say "Well, they were both division-winning teams, so we can assume
that they are equivalent offenses without Bonds and Puckett."  It just isn't
true.

>ok then what percentage of total LEAGUE production did the three players make?
>This business of saying so many runs above average is skirting the issue. 
>What was the average?  Lets add that in and then compare the three.

Fine; I'll look it up.  I don't think the "above average" way of looking at
it is skirting the issue, though.  No matter what the baseline is, Bonds will
still be about 28 runs ahead of Puckett, and Puckett will still be about 25
runs ahead of Salazar.

>>>Furthermore I suggest that the number of players
>>>whose MLV lies between Salazar and Puckett is FAR greater than the number of 
>>>players between Bonds and Puckett.  
>
>>Roughly double.
>
>Double?  You say further down that there were only 18 or 20 players better
>than Puckett in the AL.  Salazar is almost dead-on average by your reckoning.
>Does this mean that there are only 54-60 players better than average in the 
>AL assuming AL average is approximately the same as NL?

Yes, that's exactly what it means.  Because these players are better than the
sub-average players, they tend to get (with a few notable exceptions) more
playing time, and thus draw the average up.  In addition, of course, to the
fact that one player who is 40 runs above league average will have a stonger
influence on the mean than one who is 20 runs below the league average.  The
talent distribution is pyramidal, and the mean lies fairly far above the 
median.

>>My point is that, last year, Puckett was *not* among the elite.  He was about
>>the 18th or 20th best player in the AL, but was only *half* as valuable as
>>Bonds.  The ordinal ranking isn't important; it just shows that talent thins
>>out as you get up into the elite classes.
>
>The 18th or 20th could become #1.  

No, it couldn't.  That's my point.  The 18th or 20th player would have to
show a huge % improvement to become the #1 player, while the #40 player would
only have to show a mild % improvement to become the #20 player.  The spacing
between ordinal positions gets bigger and bigger as you get toward the top,
until the #1 player is significantly better than the #5 player, while the #25
player is almost as good as the #20 player.

>>And I still don't understand why you would look at it as a percentage of team
>>production, rather than in absolute runs.  Total runs win pennants.  Percent
>>of team production is just a measure of how unbalanced the team offense is.
>
>Yes but it might be enlightening to find out what Minny's chances would have
>been without Puckett and likewise for Bonds, Carter and Gant.

Oh, I agree completely.  I just don't think that %-team-runs-generated is the
way to measure that.  In fact, if you just assign one extra win for every 10
runs generated above average, you get a reasonably accurate estimate of the
marginal contribution.


-- 
        David M. Tate        | "And that inverted Bowl we call The Dome
   dtate@unix.cis.pitt.edu   |  Whereunder crawling coop'd we field and bat,
   Edward "Mike" Fitzgerald  |     Lift not your eyes to *it* for help--for it
     from "The Ruthaiyat"    |  Will drop the tow'ring fly upon your hat."
Newsgroups: rec.sport.baseball