I'm going to fall for this one... WAR is a great tool to get a quick overall valuation on a player and is easy to understand as a concept (not calculate). Use of WAR helps bring "old schoolers" closer to the "new school". It is one of the better single number valuations. But, in my mind, we can't quite use it as the end-all-be-all just yet because it has a ways to go in a few areas -- - defensive metrics: it's crucial to include this in player value, but we just aren't incredibly accurate at putting values on this today (especially for C, 1B) - positional values: this is accounted for and a large factor, but we miss team specific situations, ie - when a player may not be at his best value position due to roster composition. - situational hitting/pitching: certain players are more skilled in this than others and we can't properly value the player capable of grounding to the right to score/advance a runner compared to those who swing away. So, as long as we keep a margin of error in mind and don't try to use it to proclaim that my guy with 3.6 WAR this year is better than your guy with 3.4 WAR... then let's get our WAR on.