From: grabiner@math.harvard.edu (David Grabiner)
Newsgroups: rec.sport.baseball
Subject: Re: NL ROY: More Fuel for Debate
Date: 1 Oct 92 19:36:54 GMT
Article-I.D.: birkhoff.GRABINER.92Oct1153652
 1@blue.cis.pitt.edu.UUCP><1992Oct1.051945.18140@leland.Stanford.EDU>
Organization: /etc/organization
In-reply-to: claudius@leland.Stanford.EDU's message of Thu, 1 Oct 92 05:19:45 GMT

In article <1992Oct1.051945.18140@leland.Stanford.EDU>, Nelson Lu writes:

> In article <6551@blue.cis.pitt.edu.UUCP> genetic+@pitt.edu (Dr. Dave) writes:
>>Thus spake claudius@leland.Stanford.EDU (Nelson Lu):
>>
>>But that's not true, either.  You're saying that one Barry Bonds would
>>contribute just as many runs per out in an average lineup as he would when
>>surrounded by other Barry Bondses, and that's just plain false.

> But isn't that also a problem with MLV?  That is not a problem that is
> unique to RC/27.  Brett Butler will contribute different number of
> runs when surrounded by a lineup of Pete O'Brienses than when
> surrounded by Jeff Husons.  But you still have to come up with just
> one number for Butler.

Correct.  The assumption of MLV is that the player is in an average
lineup; thus it measures the player's value to such a team.

>>Normalizing by outs consumed does *not* correct for the interaction effect
>>in RC, by which a player with balanced OBP and SLG gets credit for batting
>>with lots of runners on base *and* for converting them efficiently, *and*
>>for being driven in at a very high rate.  In a real lineup, there wouldn't
>>be that many runners on base to convert, and the following batters wouldn't
>>convert the player in question as frequently, even if the player in question
>>put up exactly the same numbers.  RC overestimates the *marginal* value of
>>individual OBP and SLG, due to this self-compounding effect.

> I disagree to a small extent.  Why should we penalize Eddie Yost-type
> players just because GMs fail to see their value offensively?  A player who
> has a high OBP and high SLG should not be penalized by the fact that teams
> stock their roster with low-OBP/high-SLG players.

Because it isn't a matter of their being used effectively.  No matter
how you use Frank Thomas, he won't bat behind players whose OBP is .450,
because there aren't any others on his team.  But RC gives him more
credit for a home run, because it assumes that the home run is hit on a
team with a .450 OBP.  MLV assumes that the home run is hit on a team
with a .340 OBP, because the team has eight average hitters and Thomas
batting third.

Are Frank Thomas's homers more valuable than George Bell's?  If
anything, I would say the opposite, because Thomas cannot be on base for
his own homers.

And as for the misuse issue, Randy Milligan's MLV, like his RC/27,
doesn't depend on his incorrect place in the lineup.  His team would
score more runs if he batted second, but he wouldn't have a higher MLV,
except for the effect of increased playing time.

>>>2.	MLV does not account for the effects of the running game or for a
>>>	player who grounds into double-plays a lot.
>>
>>DPs, no.  Stolen bases can be added in as 0.3*(SB-2*CS) added to TMR.

> But isn't there a point of diminishing returns for stolen bases?

The .3 is from Linear Weights, and is probably too high for regular
base-stealers.  I would normally use .2.

>>>3.	Since you use league averages to derive MLV's, it gives no indication
>>>	of how much value a below average player might have.
>>
>>I disagree.  It tells you how many fewer runs you will score with this guy
>>than you would with a league average guy.  What other measure of value did
>>you have in mind?

> What I mean is...

> Eric Karros has some value this year, despite being below average.  How
> much is that value?

> By using MLV, the *more* Karros plays, the more he gets punished by getting
> more and more negative MLV.

This is a problem with MLV, because it measures runs above average.
Sometimes, this is what you want to know, but a player's value is better
measured by runs above replacement level.  

MLV could be adjusted, as you (Nelson) have done with RC, by computing
the replacement level of marginal runs per out at each position, and
subtracting this much from the player's marginal runs for each out he
made.

With this adjustment, a player who played the full season at an average
level of performace for his position would be worth +18 runs; if he
played only half-time, he would be +9 runs.

And an average player does have value; the Toronto Blue Jays would be
quite happy to have an average shortstop now, instead of Lee, Griffin,
and Zosky.

--
David Grabiner, grabiner@zariski.harvard.edu
"We are sorry, but the number you have dialed is imaginary."
"Please rotate your phone 90 degrees and try again."
Disclaimer: I speak for no one and no one speaks for me.