Hippeaux at It’s About the Money investigates the problems with the super-stat WAR. A good read. I generally avoid using the metric, if not necessarily for the reasons Hippeaux lists then because I find it massively un-fun to rely on a single imperfect stat to compare baseball players. It’s good for quick-and-dirty evaluations, but I’d always rather see the components of a player’s WAR than his WAR itself.