Fielding Linear Weights Introduction

I'm currently in the long process of making a fielding system that I hope will work.  I'm going to give you some main insight on the topic so far.  I think a good name for it would be Fielding Linear Weights.

A) Defense is very hard to measure for the reason being, good fielders stats such as putouts/assists aren't much different from bad fielders stats.  This is a pretty big blimp which I am still working on to cross. 

B) The basic formula is so far would be this:
Putouts+Assists divided by Errors, divided by a fixed number determined by the player's position. 

So far, I'm still working on the fixed numbers and some weights such as assists in the outfield.  The question is, how did fielding stats get so screwed up throughout the years?  Don't get me wrong we have made progress in the field with Defensive Runs Saved work.  But there has to be more to it.  Not one stat can end all discussions.  My goal is to provide my own system which will by the end of it hopefully give us an accurate measure of defense.