From: tloughin@IASTATE.EDU (Thomas M Loughin)
Newsgroups: rec.sport.baseball
Subject: Re: Cecil signs :-( :-( :-(
Date: 26 Jan 93 19:40:40 GMT
Reply-To: tloughin@IASTATE.EDU (Thomas M Loughin)
Organization: Iowa State University

In article <2531@blue.cis.pitt.edu>, genetic+@pitt.edu (David M. Tate) writes:
> 
> What I want to do is to explain wins.  I want to point to a team and say 
> "They won 87 games; what were the individual contributions to that total?"
> Now, since winning is BY DEFINITION relative to your opponents' actual
> performance, and not to some hypothetical replacement level, it seems only
> reasonable to use your opponents' actual performance as the yardstick by
> which to measure where your wins came from.  That's why I advocate the use
> of league averages (or, actually, the average of everyone in the league but
> you) as the correct baseline for this sort of analysis.  It's a retrospective
> look (as Bob Davis correctly pointed out) at what happened in the past; not
> an attempt to gauge how hard or expensive or whatever it would be to replace
> the performance of a given player.
> 
That's right.  I agree with you -- league average is .500 for winning 
percentage.  Most sensible prediction or evaluation techniques intended to 
evaluate individual _contributions_ to winning will do so from the assumption 
that a teamful of purely average players should have exactly a .500 winning 
percentage.  

> So, for example, the answer to "How can you say that a 12-12 pitcher with
> 200 innings is 'worthless'" is (a) that's an above-average performance, I'll
> bet; (b) not 'worthless' but 'win-neutral', which is different, and (c)
> because the ability to pitch lots of innings has prospective value (as a 
> hedge against having to use a worse pitcher), but no *retrospective* value
> beyond the quality of those innings.
> 
This is a good example, and I think that much of this argument, as you suggest,
is over the use of the word "value."  In my eyes, the player's "value" is 
what he offers to a team that is above or below what they would have to use
in this player's absence.  This is what has been termed "replacement value."  

Like your 12-12/200/3.70 pitcher, the _value_, then, is measured by the 
production he is providing, given that they would have had to pitch *somebody* 
for those 200 innings.  His _contribution_ to increasing or decreasing the 
team's winning percentage from .500 is virtually nil.  

Dave, if we all agreed to use this terminology (or something else that 
distinguishes between the two measures), would you still have any doubts that 
a SS with an SLG 50 points above average (or 100 above, or whatever) is more 
*valuable* than the 1B slugging +50 (or +100...)?  You will claim, of course, 
that they make equivalent _contributions_.

In that case, I wonder:
Does it make any difference (in terms of run-scoring ability, and hence, in 
terms of wins and contributions) whether a team's .360 cumulative slugging 
average comes from one 1.000 slugger and eight .280 sluggers, or from nine 
.360 sluggers, or from eight .405 sluggers and one .000 slugger?

Hmmmm, not another can of worms...

-Tom.
Newsgroups: rec.sport.baseball