Uhh... The various sabremetric folks are still trying to figure out a consistent WAR for players!
I could put together something for managers by the end of the week. It wouldn't be very good, but if I threw in enough complicated math in various places, most fans would just treat it as a "black box" (e.g., magic), and would choose either to believe it or not believe it - probably largely on the basis of whether it gave results that reinforced their beliefs or not!
Yeah, that'a comment on WAR - and in particular on the defensive metrics that get folded into WAR (one way or another, depending on which flavor of WAR your pastor endorses).