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...you can read the PCA manifest...I don't know if you have time to go through the whole thing or not...it's 75 pages (James' explanation of Win Shares is similarly lengthy...hard not to cover a lot of pages with verbage when explaining something as complicated as a full uberstat metric system)...I produced the explanation for anyone who wanted a copy.
To clarify the main idea of the system though, I use Pythagorean theory (hence...Pythagorena Comparative Analysis) to set the margin for performance, rate teams and players relative to the margin, and give significant additional value to performances that imply a forced sub-marginal performance from the opposition.  The system still uses the linear-above-margin approach for dividing credit among players (just as James does), but my marginal baseline is significantly higher than his was and the concept of supermarginal performance (adding a second value enhancement to player performances that imply the opposition is submarginal when facing a given player) places additional emphasis on superstar caliber play.  Think of the supermargin as adding the negative wins a supermarginal performance creates in the OTHER team to the team being analyzed.  I call this quasi-exponential because the supermarginal value is pythagorean, so the further above the supermargin you are, the higher you rise above your peers.
I'm not sure I discussed the supermargin in detail in the manifest...I was mostly laying out the logical foundation for my approach to sabermetrics...but I still think it's worth reading if you are actually interested in how I did my work.  PCA is a look into a little time machine for me...some of the methods I used were a little primative compared to the ideas I have today (I last published PCA after the 2004 season...it's been five years).  But when I read back over it, I am still proud of all of the careful thought I put into it.