THE BOOK--Playing The Percentages In Baseball

Really good stuff.  Certainly if a manager were to use an RE or WE matrix to help him with in-game decisions, he would want to have a whole bunch of matrices and match up the estimated run environment, based on the pitcher, batters, park, and weather, with the right matrix.  Of course that just gives you a baseline to work with anyway. The actual quality and individual skills/projection of the batter or runner(s) makes a large difference as well.  The baseline is important though. If it is heavily negative or positive, that tells you that no particular player will likely swing it in the other direction.  If it is close to zero, that tells you that the relevant players make a big difference in terms of choosing one alternative or the other.  In both of those examples, the decision becomes a lot easier.