Football fans no doubt have heard of the phrase "coaching tree" over the years. The concept centers on the idea that great football coaches often pick top-notch assistant coaches, who go on to work for other teams. Sometimes those assistants have learned their lessons and match or even top the accomplishments of their mentors; sometimes they fall short. But it's always interesting to trace the genealogy of a particular coach.

The concept may have gotten off to a flying start in the late 1950s with the New York Giants. The head coach of the team then was a man named Jim Lee Howell, who won quite a few games and one championships back then. But he's been overshadowed by his two main assistant coaches, who would be called coordinators today. Vince Lombardi was one, and Tom Landry was the other. You can find out more about them by visiting the Pro Football Hall of Fame in Canton.

Bill Walsh has a coaching tree, thanks to his great work with the San Francisco 49ers. There's an indirect connection there between Walsh and Mike Shanahan, who popped up on the Niners' staff during the early 1990s. Shanahan had some success as a coordinator with the Broncos in the 1980s, and helped develop Steve Young into a championship quarterback with the 49ers in the early 1990s. From there he was instrumental as Denver's head coach toward the claiming of two more titles.

Taking notes along the way was Mike's son, Kyle. If you look at the right footage from those good times, you sometimes can see Kyle hoping the cords to the headphones that his dad wore on the sidelines. (Soon that job disappeared when everything went wireless.) You could tell that Kyle had a strong interest in the coaching business, and you could guess that he'd be good at it.

Sure enough, that's essentially what happened. Kyle was part of a group that has had a strong influence on football philosophy in the NFL. Author Michael Silver chronicles their story fully and completely in his frequently fascinating book "The Why Is Everything."

These were coaches who worked hard and played hard, sometimes to their own detriment. If someone had came up with an idea about a particular aspect of the game, it was welcomed into the discussion no matter what the source was - but it had to be defended fully loudly from the comments of the rest of the coaches. In others, the presenting coaching had to explain why his idea was sound ... and the "why" was everything in that setting. It was almost a laboratory for coaching.

If you are a fan of the NFL, you know the names involved: Sean McVay, Raheem Morris, Matt LaFleur and Mike MacDonald. They all reached the exalted status of head coach in the NFL. McVay even won a Super Bowl, and Kyle Shanahan has come close. Today there is still a friendship there most of the time, but they also are rivals too. There's nothing better they like to do than beat the other guys.

What's fascinating, though, is that Silver does a great job of getting those involved and their associates to open up so much about the past decade. Little seems to be off the record here. Therefore there are plenty of great stories about such topics as Jared Goff's ups and downs with the Los Angeles Rams, Trey Lance's mostly downs with the 49ers, Tua Tagovailoa's emergence with the Miami Dolphins, and Aaron Rodgers' awkward departure from the Green Bay Packers. Other tales about football come out as well, such as Robert Griffin's problems in Washington.

In other words, this is like sitting down with some assistant coaches after practice over a few beers, and having them swap stories. Yes, the language is rather profane at times, although in some cases it seems to add to the authenticity of the feelings expressed.

The one complaint that some might have about the book deals with the fact that it can be a little technical. Not all of the readers will be so well versed with football terminology that they'll understand the various schemes and plays that are outlined here. So this isn't really a book for the casual fan.

But for the others, "The Why is Everything" is as close as we'll get to finding out what's really happening in pro football. They'll enjoy every page.

There can't be many more stressful jobs than that of an NFL coach. The amount of work put in designing plays, coaching the players so that they understand their place within the system, making in game decisions and having to immediately answer to the media when things go wrong. Then there's the regular stresses of being a manager such as dealing with different personality types. All of this done with tens of millions of people thinking that they know better than you how to do your job. Getting fired at some point is almost guaranteed. This is the world that Kyle Shanahan was born into, and the world he's been altering for the last decade.

The Why is Everything is long for a sports book, at around 450 pages. To be honest, I'm not sure I would have read it if I'd known how long it is (I got an ebook copy). And yet I'm glad I did. It starts a bit slow, introducing all the characters, but it has a propulsive narrative that once it got going I knew I'd finish the book. The book follows Kyle Shanahan, from his origins working for his father with the Broncos, right up to the end of the 2023 season. It branches off to include the stories of other members of his coaching tree including Sean McVey, Matt LaFleur and Mike McDaniel among others. I found it very interesting how different the personalities were between these coaches, even amongst similar football minds. Kyle Shanahan is almost a tyrant. Loud, cocky, abrasive, demanding. Sean McVey, who had the success of a Superbowl win early in his career uses more inspirational tactics, except for one period dealing with the QB Jared Goff, a time which he came to regret. Mike McDaniel is the strange chill guy who seems most like a normal human. These guys are more interesting than I would have expected from the stereotypes I had about NFL coaches, mainly that they're all basically Bill Belichick in spirit.

I think it's important to note that this book is about NFL coaching, and not about NFL football. What football there is in this book is almost incidental, like how the word carburetor might come up if watching an F1 race. In this book, the players are just cogs to fit into the coaches system, and they often fail to play in the way the coaches demand. A large part of the Kyle Shanahan style of coaching is hammering out individualism from players and just get them to follow the damn playbook. It works though, it's unique compared to other football books.

I come to the NFL as a fan of the chaos of the action, of seeing grown men smashing into each other. Reading this book that really gets into the details of play design gives me a deeper appreciation of the game. There is some more technical football terms in here when describing plays, so I wouldn't recommend this book to a football beginner, but anyone who has been watching for more than a season or two should follow along just fine.

The Why Is Everything is a well researched and fascinating look at the NFL and the new crop of coaches who have developed and changed the league into the modern National Football League.