From: silber@m.cs.uiuc.edu (Ami A. Silberman)
Newsgroups: rec.sport.baseball
Subject: Re: Simulation Games
Date: 23 Jul 92 23:35:31 GMT
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL

mcmath@csb1.nlm.nih.gov (Chuck McMath) writes:

>I'm in APBA (Computer) and PTP (Board) leagues, and one big difference
>between them is the way they handle L vs R matchups.  PTP uses the actual
>left/right pitching/batting stats on their cards, whereas APBA uses a
>'platoon factor'.

>For example, take Jerome Walton.  He batted .195 vs LHP and .239 vs RHP. 
>His PTP card reflects this, in that he gets more hits vs. RHP.  They also
>have separate ratings for power vs. each pitcher type (Walton has NO
>homeruns vs LHP and a few under RHP).  The same is true for pitchers - take
>Curt Young.  He allowed LHB to bat .212 while RH batters did .312 against
>him.  He also gave up fewer home runs to LH batters.  All this is reflected
>in his card.  APBA, on the other hand, rates a player - say Walton - with a
>particular set of batting statistics, and then, for example, would give him
>a '1' platoon factor (don't know if that's the actual number, I don't have
>that info here).  That means when facing a pitcher throwing the same way he
>bats (i.e., R vs R) they reduce the chance of a hit, etc (I don't know how
>this is done, since it's done on the computer).  I don't know how this
>affects power either, but I expect that they decrease it.

>APBA makes a big deal about how you can't accurately model L-R differences
>based on such few samples as a normal batter has over the course of a
>season.  I don't know if that's true or not, but if I understand it
>correctly, the APBA technique is flawed also - for instance, I don't
>understand how they rate switch hitters who bat much better/worse one way
>than the other.  The ones I've all seen have a platoon factor of 0.  Plus I
>don't know how they account for players who hit BETTER vs a pitcher who
>throws from the same side as they bat (don't know of this type of batter
>exists, but I'd be willing to bet somebody out there is like that!).

APBA doesn't handle it all that well, but their idea is basically correct.
I'm in a PTP league, and one of the things I've noticed is that we are all
very cognizant of extreme and inverse platoon differentials. In real life,
if you rate platoon differentials on a scale of -2, -1, 0, 1,..5 with
5 being extreme, and -2 being a fairly large inverse platoon differential,
and if we could assign players their ideal platoon differential (what they
would hit over, say, 5000PA) most hitters would end up with say, a 2, 
most switch hitters with a 1, and most pitchers with a 2. If you base it on
a given season, you'll get some 4s and 5s, some -2s and -1s. If you base it
on a players last three seasons, you'll still end up with some 3s and some
-1s or -2s, but nowhere nearly as many. You won't have Sid Fernandez in '91
being hell on righties etc. I wish that PTP would go to this system for
both hitters and pitchers, right now its often better to bring in a righty
pitcher (who may have pitched all of 30 innings) to face a lefty than any
of one's lefties (some of whom may have better overall stats) etc.
It may not be quite as "statistically valid", but a) the validity is
not evidenced if the players are used uncharacteristically, and b) in this
case is may be preferable to sacrifice statistical validity for the sake of
simulation and versimilitude.
-- 
ami silberman - janitor of lunacy
	silber@cs.uiuc.edu
Newsgroups: rec.sport.baseball