BPA V0.9

The following is my formula for calculating BPA (bases per plate appearance). Numbers followed by an asterisk (#) are numbers that I am not certain of, but are educated guesses (hence the V0.9).
A=1b
B=2b
C=3b
D=HR
E=BB
F=IBB
G=HBP
H=SF
I=SH
J=SB
K=CS
L=PO (picked off)
M=SO (strike out)
N=GDP
W= The probability (league average) of an AB with at least one man on base
X= League OBP
Y= The probability (league average) of an AB with a man on third

BPA=[(A(1+(W*1.0202#)))+(B(2+(W*1.36#)))+(C(3+(W*2#)))+(D(4+(W*2#)))+(E(1+((X*.5#)+((X^2)*.25#)+((X^3)*.25#)))+(F(1+((X*.25#)+((X^2)*.1#)+((X^3)*.001#)))+(G(1+((X*.5#)+((X^2)*.25#)+((X^3)*.25#)))+H+I+J-K-L-(N*2)-(M*Y)]/PA

Forgive the length, I promise it's necessary to give the full picture.
Anyway, the values of each outcome (that has a multiplier) based on 2008 statistics are:
1b=1.4605
2b=2.6139
3b=3.90274
HR=4.90274
BB/HBP=1.20056
IBB=1.09515
K=<.10957>

Feedback, if anyone out there is reading, would be appreciated.