If the title of the book appeals to you, you're going to love this book. I did.
In the book's first part, lasting 62 pages, Chris Jaffe derives three metrics for both evaluating and describing managers' performances. These are expanded versions of articles that originally appeared on various baseball analytical websites. For the key metric, Jaffe examines five aspects of team seasonal performance above or below expectations shaped by the team's surrounding seasons. If a manager has a sufficiently long track record, Jaffe assumes that the performance above or below expectations is due to the manager and not randomness, luck, or other influences. Obviously, that's an artificial assumption as Jaffe recognizes, but it is the best attempt at trying to both quantify a manager's value and describe what he does well that I've seen. There are definitely problems with the metric, most notably that managers blessed with strong talent tend to do well, but it's a start.
That first section can be a bit dry, so if you're impatient, feel free to skip chapter 3.
The last 70% of the book is the payoff. There are mini-chapters on every manager with a moderately long major league career applying Jaffe's metrics and describing what the manager does well. This material is just terrific, with plenty of original observations. Jaffe's metrics give him an informed perspective that you won't read elsewhere. This portion of the book is not as quantitative and makes for better reading. The last two chapters, on current and recently-retired managers are the best portions of the book, so peek ahead to read a minichapter on one of your favorite recent managers to see if you'll like it.
One downside is that while the book's subtitle indicates it covers through 2008, in some respects it stops in 2006 due to the restrictions of Jaffe's methodology. Nonetheless, I very much liked it and give the book a 5-star rating.
Note that while the book is a bit expensive for a mere 288 pages, there is plenty of text per page, so it's not a bad bargain.