Rob Arthur for FiveThirtyEight:
WAR looks like a single easy-to-understand stat, but it’s the product of a complex model. That model integrates information on all the ways a player provides value: his hitting, fielding, baserunning and (for pitchers) pitching. The WAR you find at, say, FanGraphs or Baseball-Reference.com is an estimate of all those categories combined.
However, like all statistical estimates, WAR calculations come with uncertainty. Here’s where things get pretty statsy, so bear with me: You’re about to get a crash course in confidence intervals. The true value of a player varies from what you find on the leaderboard — but we’re not sure by how much.
Disagreed. There is one single stat which should define the 2015 AL MVP race: the playoffs. And the Angels are on the outside looking in.