I'm pretty sure you mjst have recommended this to me Sloop.... finished it yesterday :
Took two days.
Absolutely captivating read about Belichick, and the guys from the Patriots back room staff who went 'out on their own' after working with him (Pioli, Dimitroff, McDaniels, Crennel, Weis etc).
If you're interested in the behind the scenes at an NFL team, this is wonderful. Gives a real insight into the different responsibilities of each role, how that varies from team to team, how they approach both free agency and (particularly) the draft (hence 'the war room') and the salary cap too.
It's really enlightening to see just how brilliant Belichick has been in evaluating draft choices so accurately, and getting value throughout. The accumulation of picks is incredible and how they are used to balance the salary cap is key (those lower picks filling roster spots instead of more expensive senior players etc). It's also interesting to read that he isn't faultless and sometimes gets it spectacularly wrong.... sometimes.
A really enjoyable book, that makes what could be a very dry subject really interesting and informative.