I want to get a book or two on Sabrmetrics for my Dad for Christmas, and I'm curious if anyone has read any good ones. He's a very astute (in the sense that he understand the balk rule, and who Gavvy Cravath was) fan, but his stats-base consists of RBIZ and WINZ and such, with nothing more explanatory than OPS. I've tried explaining concepts such as WAR, but I'm struggling to get through. I think he's open to the concepts, I just need help breaking through. I found Understand Sabermetrics on Amazon.com, which seems promising, but I'd like to get a first-hand review.