I know there is a reason for the weights that WIS has assigned to the pitcher and the hitter's respective influence over the outcome of each PA.  I used to know where it came from but now I can't remember.  Is it in The Book?  Or where?  Thanks in advance.

I bumped it.

I was hoping I'd just figure it out, but what does bumped mean?   I'm now thinking it means that it will appear in a search of more recent items...but in this case, what would one search for to find this?  

The more recent forums should appear at the top of the list.

I "bumped" the decision tree thread (with the math in it) to the top of the forum thread list.

So it looks like the reality is we don't get to see any of the inner workings of the math on this one.  If it doesn't come from an outside resource it's not worked out anywhere else.  And "based on league-adjusted variance" is a bit cryptic to me.  Are they just assuming that the relative importance of each participant is directly proportional to the variance across the league?  That seems like it would be a huge mistake, since there are a larger number of batters who are valued for a larger variety of things.  This suggests that batters should always have a greater degree of variance in performance, but that doesn't necessarily imply at all that batters play the bigger role in determining outcomes of plate appearances.