In The Pro Football Historical Abstract , author and sports statistical genius Sean Lahman presents a revolutionary reevaluation of football statistics and, a la Bill James, comes up with stats such as "adjusted yards" and "Q-Ratings" to more accurately assess player performance. Using these methods, and his many years of experience in sports statistical publishing, the author presents his all-time rankings of players at each position. He also discusses how the game has changed from decade to decade, and how these changes must be considered when comparing modern players like Tom Brady, Dan Marino, and Emmitt Smith with players of past eras, such as Sammy Baugh, Jim Brown, and Johnny Unitas.