I found this interesting article that quotes Bill James, who was a pioneer of Sabermetrics (derived from the acronym SABR from Society for American Baseball Research), that is titled - Bill James: not a “statistical guru,” not impressed by WAR - http://hardballtalk.nbcsports.com/2014/10/29/bill-james-not-a-statistical-guru-not-impressed-by-war/
The following is an abstract from the short article:
And you wanna know what else? He’s not at all impressed by Wins Above Replacement (WAR), the stat that has become a proxy in the larger battle between stat-oriented people and traditional baseball people:
“Well, my math skills are limited and my data-processing skills are essentially nonexistent. The younger guys are way, way beyond me in those areas. I’m fine with that, and I don’t struggle against it, and I hope that I don’t deny them credit for what they can do that I can’t.
“But because that is true, I ASSUMED that these were complex, nuanced, sophisticated systems. I never really looked; I just assumed that the details were out of my depth. But sometime in the last year I was doing some research that relied on these WAR systems, so I took a look at them, and … they’re not very impressive. They’re not well thought through; they haven’t made a convincing effort to address many of the inherent difficulties that the undertaking presents. They tend to get so far into the data, throw up their arms and make a wild guess. I don’t know if I’m going to get the time to do better of it, or if it will be left to others, but … we’re not at anything like an end point here. I assumed that these systems were a lot better than they actually are.”
Bill James seems like rational person who loves baseball. He was also instrumental in analysing baseball stats and realizing the limitations of some stats such as batting average and developing a better stat called secondary average - https://en.wikipedia.org/wiki/Secondary_average (amongst many others)
I like most of the new Sabermetric statistics. However, I agree with Bill James, in that I am not really impressed by WAR since the metric supposes to determine wins better than a replacement level player. However, I believe that when separated into offensive WAR and defensive WAR it gives an additional indicator of a players performance in each category (as opposed to believing that it actually determines win contribution).
Although Bill James was a pioneer of Sabermetrics, he doesn't seem to be a Sabermetrics extremist.