I'm certainly not saying that stat doesn't have any value, because honestly I have no idea what it is, but Wood is #32 (just behind our old friend Ohman). Certainly you would have to agree he's a top 10, if not top 5, reliever in the game. It's expected wins over a replacement level pitcher. However, it goes a step further by adjusting for quality of hitters faced. That way you can't just come in and face garbage players each game and show off a .80 WHIP -- it's showing how good the guys you faced were and how much better you were than a replacement pitcher.