How are we supposed to interpret all the new stats in baseball, and which ones have proven the best?

Let's say you really want to understand all the various new metrics that have been applied to baseball in past years (yes, yes, I know, plenty of people are just fine sticking to batting average and RBIs), but all the plusses and weighted numbers start to make your head spin.They make mine spin, too. So I tried to make some sense of it with Curt Hogg, our Brewers beat reporter.JR: Let's start as broadly as possible. If I'm trying to evaluate a player, especially a position player, what stats should I be using, and why?CURT: The short answer? WAR is the best metric. While it's not without its flaws, it is the best catch-all statistic in baseball. Different sites (FanGraphs, Baseball Reference, Baseball Prospectus, etc.) all use their own specific formula to calculate a single number that measures, well, how many wins above a "replacement-level" player a specific player was. It takes into account all aspects of the game: hitting, fielding and base running.JR: I remember last year, Jace P...