Michael Lewis shot to fame in the late 80s with his book on the stock market - Liars Poker. He also revolutionized baseball with his book - Moneyball in early 2000s.
If you think "The Blind Side" will revolutionize american football, the same way - he is atleast 15 years late and the book is not going to add any new insights to the way the game was transformed by free agency. The closest that american football has in conjuction to transformation is the growth of statistical analysis in the game and the growth of websites like Football Outsiders.
However the book is worth reading once for the simple reason that it summarizes the growing importance of the left tackle position - the most unglamorous but highly paid role in football as well as making the biography of Michael Oher interesting.
While the books on succesful athletes can be found plenty a dime, it is purely superb move to publish a book on a player who is making child-steps in college football and is not likely to hit the NFL draft till 2008.