Teaches you stuff you should already know, but don't tend to think about when watching a game. It may seem a bit dated as many of the players referenced as examples were from the 2003 Red Sox and Yankees.
mellochild -
This book is amazing. As a die-hard Red Sox fan for twenty-five years, I thought I was an old pro when it came to understanding the game - "The Rem-Dawg" made me look like a rookie! From the mechanics behind every pitch to what position to take in the field depending on who's at bat; from the way hitters work the counts to the way they bust slumps; from stealing signs to stealing bases to stealing a few zzzz's on the plane after a night game followed by a day game... this is the most definitive baseball book that I've ever read. A must for casual fans and know-it-all fans like me - this will make you feel like you're on the field! (Or at least on the bench. Natch.)
