From: genetic+@pitt.edu (David M. Tate)
Newsgroups: rec.sport.baseball
Subject: Re: Cecil signs :-( :-( :-(
Date: 26 Jan 93 16:57:20 GMT
Organization: Department of Industrial Engineering

tedward@cs.cornell.edu (Edward [Ted] Fischer) said:
>In article <2531@blue.cis.pitt.edu> genetic+@pitt.edu (David M. Tate) writes:
>>
>>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.

>>Is this more clear?

>Not really.  For your purposes, any baseline will do.  

In theory.  In practice, no, because we'd have to normalize for nonlinearity
in response.  We know a nice simple relationship between run differential
from the average and W/L record.  We do not know any such relationship for
run differential from any other baseline.  We don't even really have a clear
idea of where replacement level *is*, while average is easy to find.

In short, any baseline will do, but only average will allow us to follow
through and actually do the analysis, given current models.

>Using your
>argument, since we are interested in winning pennants, why not compare
>players to the average player on a pennant-winning team?  

Because there's no such thing.  There is the actual performance that the
pennant-winning team got, but that's not an average.  It also falls prey
to the nonlinearity I was talking about above.  If you have Honus Wagner
in your league, and the Pirates win, every shortstop is a horrible liability,
whereas if the Pirates get squeaked out by the Giants, they aren't.  That's
a silly consequence, and a good reason to avoid using that sort of analysis.

>If you are asking the question of "how many games will the team finish
>above .500", it might make sense to use the league average as a
>baseline.  

That's essentially what I *am* asking, since any other reference point shifts.

>But you might as well ask "how many games will the team
>finish above .250 (or whatever replacement-level is)."

If I could figure this out, it would be equivalent.  But why make life hard?

>And I still disagree about the Pirates and Bichette.  The Pirates at
>the start of the season did not have a surplus of outfielders.  They
>do not (as far as I know) have many top OF prospects in the minors.
>They are unlikely to have a team in the next five years where *all*
>of their outfield slots are filled by players better than Bichette.

On the other hand, Bichette will certainly not make the difference between
contending and not contending, nor will he be a major box-office draw.  So,
either they'll compete without him, or they'll not compete.  Either way, it
makes no sense to sign an aging mediocrity.


-- 
       David Tate        |"Something there is that doesn't love a wall,
 dtate@unix.cis.pitt.edu | That sends the screaming liner over it 
 Prof. of Story Problems | And spills the bleacher-dwellers from their seats."
 Member ORSA, TIMS, SABR |  	"Fenway Wall", Robert Frost          
Newsgroups: rec.sport.baseball