In an interesting week on fangraphs.com, Jack Moore published several interesting and probably long overdue articles on reliever leverage and how it pertains to their value as indicated by their free agent salary (Overdue generally, not from Jack Moore specifically). Through these articles, Jack Moore analyzes WPA as a possible measuring tool for determining reliever salary as opposed to the conventional $/WAR measures because relievers, unlike other players, largely have their leverage determined for them by coaching decisions. As a result, relievers signed to be put in high leverage situations by their coaching staffs probably have their value unfairly determined to be albatross by traditional measures.
With this new and probably superior way of thinking of high leverage relievers available to us, it makes sense to analyze reliever performance incorporating both expected performance in terms of WAR and in terms of leverage. Jose Valverde, in particular, is an interesting case from a number of different perspectives. Valverde has outperformed his expected FIP and xFIP over the course of his career by a considerable margin, one that probably cannot be ignored. In addition, Valverde’s actual value to the Tigers must be analyzed in terms of his leverage as well as traditional value measurements.