Another "value added" paper
The "Value Added" approach for baseball – where a player is credited with the increase in run expectation or win probability arising from his contribution – seems to keep getting independently reinvented. (For instance, see the bottom of page 3 here.)
Here's the latest, from the Retrosheet website, by Kyle Y. Lin and Ken K. Lin. The authors do not cite any non-academic references. They use wins as their measure instead of runs. And they include a nice explanation of the algorithm for recursively calculating theoretical (Markov) win probabilities from Retrosheet data.