If you read my review in June, you know how much I liked Mark Baker’s book, “The Game Changer: A Simple System For Improving Your Bowling Scores.” Baker’s new DVD “The System” expands on that book and brings it to life, so to speak, making it perhaps the best purchase a bowler seeking improvement could make — short of actual in-person coaching from a top coach. The retired PBA Tour champion has become one of the world’s top coaches, best...