From: mjw@Xenon.Stanford.EDU (Michael Wolverton)
Subject: Re: Cecil signs :-( :-( :-(
Organization: Computer Science Department, Stanford University.
Date: Sat, 23 Jan 1993 00:36:31 GMT

In article <2356@blue.cis.pitt.edu> genetic+@pitt.edu (Dr. Dave) writes:
>I'm going to claim that useful things, in general, have two different kinds
>of value: use value, and market value.  In an imperfect market, these two are
>seldom the same.  The classic example is a used car.  *Any* car that runs has
>a use value equal to what it would cost you to get around town if you didn't
>have a car that runs.

But I think you're using replacement value in this car analogy: you
evaluate your car by looking at what it would cost you to perform its
function IF YOU DIDN'T HAVE THE CAR.

You do the same with baseball players: look at what you get when you
*do* have the player, and look at what you'd get if you *didn't* have
the player.  Subtract the second from the first, and that's your
player's value.  What you'd get if you didn't have the player is a
replacement level player.

>Now, I claim that this applies to baseball players, too.  A player's use value
>is what he does to your chances of winning when he plays.  Since winning is
>defined as scoring more runs than your opponent does, this value consists 
>solely in how much he contributes to your run differential.

I'm with you up to here.

>Run differential
>is not a function of who the worst player in the league is, but rather of who
>is actually playing in the league.

Here I'm just not sure I understand you.  Isn't the worst player in the
league "actually playing in the league"?  Do you mean "getting lots of
playing time in the league"?  At any rate, I would certainly agree with
you if you claimed that the comparison metric shouldn't be the worst
player in the league.

>Thus, average value at a given position
>is the relevant baseline for use value.

This is where I lose you.  I don't see how this sentence follows
logically from anything you've said previously.  *Any* player
contributes (positively) to your run differential, provided he's
better than what you'd have if he wasn't there.  No team can fill
their roster with only better-than-average players, and any team
improves itself by replacing its really bad players with better -- but
still below-average -- players.

I've used this example before, but it's still a good one: look at the
bulk of last year's A's starting pitching -- Stewart, Darling, Moore,
Witt, Slusarski.  All below average.  Yet I really believe that a
season-ending injury to any of them (except Slusarski) would've hurt
the A's.  They simply didn't have anyone better to turn to.  Still,
with this staff o' stiffs, they won the division.  Stewart et. al. had
negative value if you use league average as a baseline, but they still
contributed positively to a division-winning club in reality.

>Replacement
>level tells you how badly your team's winning percentage would fall if all the
>shortstops in your organization were killed by a freak meteor shower, so that
>you had to go out and sign AAA players and released major-leaguers.  

It's not quite like this.  You evaluate baseball players in the same
way you evaluated your car above and in the same way you'd evaluate
anyone or anything -- by figuring out the costs/benefits of having
him/her/it versus not having him/her/it.

-Michael
-- 
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Michael Wolverton                       "Is that clear?"
mjw@cs.stanford.edu                     "No, but it's consistent!"
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