I wrote a blog post on Thursday for ESPN Insider's saber-slanted blog, TMI. It's behind the pay wall, but I think I can share the Excel file that's part of the post. If you're looking for a handy way to judge the value of a reliever, just plug in some ERA, innings pitched, and leverage index estimates for a whole bullpen, first including a reliever and then without. My article addressed the Twins loss of Joe Nathan, and the calculations estimate his loss in the 2.5 win range. You can download the spreadsheet here.