I give this 4 stars because the stars are about subjective reaction and I enjoyed reading it. On the other hand, I can definitely see you getting less mileage out of this book if aren't a fan of LaRussa, the Cardinals, or baseball, or even if you know a lot about the game. I also don't see this as having much staying power over time.
That being said, I think I would describe this book as "effectively wild" a term he uses to describe Cubs pitcher Kerry Wood. There are plenty of overwritten sentences, and even unintelligible metaphors, but overall I still found the book interesting and even exciting. Of course, I am a LaRussa, Cardinals, baseball fan.
I'm also a fan that is ignorant enough to learn something from this book. I found there to be plenty of good explanation in it, although I can imagine for some people I know the explanations might seem boring.
The last point I want to bring up is its relationship to "Moneyball". "3 Nights..." argues against the sabermetric revolution to some degree. I found the argument subtle in the sense that although does make the point explicitly at times he never let's it distract from the main story line of the book. So I found this angle added something to my appreciation to the book. Despite evidence that personally Bissinger is a douche, his point of view in this book is well presented.