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A wise longtime NFL assistant coach, scout and personnel executive told me a long time ago that there are always lessons to be learned about team building and coaching evaluations to be gleaned from the final eight clubs left standing in the league.

There are clues to trends for success to be culled from how rosters were built, which overarching philosophies these team espouse, and how their coaching staffs were constructed. There are reasons why teams reach the divisional round and beyond, and smart owners and team presidents -- especially those who are conducting coaching and/or general manager searches -- will mine these data points to help steer them to the right people.

At a time in which a quarter of the league is seeking a new head coach, and with four teams looking for a GM, now seemed like an appropriate time to conduct the exercise myself. And there are certainly conclusions to be drawn, and certain family trees to focus on. Of course, not every coach who has worked under a head coach -- or within certain coaching principles -- will be as successful as the top guy, or even nearly as successful in most places, but there are certainly some trends that stand out to me as we assess the final eight teams left standing in the NFL.

For instance, half of the teams have a head coach who is in the Kyle Shanahan/Sean McVay family tree. Shanahan, coach of the 49ers, was the offensive coordinator in Washington when his dad, Mike, was the head coach. And on that staff were assistants like McVay, who has the Rams back in the playoffs, and Matt LaFleur, who has won more regular season games the last three years since taking over as head coach in Green Bay than anyone else. And, shortly upon taking over the Rams, McVay hired Zac Taylor from the University of Cincinnati to join his new staff; Taylor's Bengals just erased a 30-year playoff win drought last week.

Pretty impressive, and the kind of stuff that tends to resonate with owners this time of year. When you look at the remaining coaches in the NFL who are on the younger side -- say, below 60 years old -- there are only six still standing, and only four offensive coaches remaining: the four just mentioned above. Mike Vrabel (Tennessee) and Sean McDermott (Buffalo) come from the defensive side of the ball, while Andy Reid (Chiefs) is 63 and Bruce Arians (Tampa) is 69 and both are far closer to the end of their careers than the beginning. 

With that in mind, it makes me wonder if, of the cluster of young offensive assistants making the rounds, Packers offensive coordinator Nathaniel Hackett, 42, ends up getting one of these jobs having spent the last three years with LaFleur. (Hackett worked previously in Jacksonville, already interviewed there, and some in the industry believe the Jaguars might be stalling the process with eyes on hiring a coach who is still involved in the postseason and thus cannot conduct a second head coaching interview this week.)

Taylor's offensive coordinator, Brian Callahan, is starting to get his first requests to interview for head coaching jobs, and if something does not come together this cycle, you can expect him to be among the hottest names this time next year. The buzz will only grow stronger. Teams have been sniffing around on Shanahan's chief run game guru, Mike McDaniel, for a few years now, and the Dolphins have him on their interview list. More will likely follow.

When you look at the defensive coordinators still alive in the playoffs, there is a certain trend that is difficult to miss as well, particularly on the defensive side of the ball. The tentacles on Reid's coaching tree spread far and wide on both offense and defense. (McDermott grew up as a coach under Reid with the Eagles, eventually becoming his defensive coordinator, while Bills defensive coordinator Leslie Frazier first coached in the NFL on Reid's initial staff in Philly in 1999 as defensive backs coach.)

Arians' staff in Tampa is getting lots of attention among those looking for a head coach, and rightfully so. It's worth noting that Bucs defensive coordinator Todd Bowles was with Reid in 2012, his final year in Philly. There is a growing sense that 49ers defensive coordinator DeMeco Ryans is a head coach in the making; he played under Reid in the coach's final season in Philly. And, of course, Chiefs defensive coordinator Steve Spagnuolo has a deep history with Reid going back to their early days with the Eagles.

The Reid and Shanahan/McVay effect is everywhere as we head into the final weekends of the season. And with not a single team yet to hire a new coach, but more teams firing them every week ... well, something has to give here pretty soon, and the path to many of these hires might go through these two particular forests.

Personally, you cannot convince me that Frazier and Bowles should not be head coaches right now; both have done the job before at this level and are leaders and teachers. (I tend to favor a defensive or special teams head coach model; years spent watching football with Bill Cowher has won me over.) I think it's ridiculous that Chiefs special teams coach Dave Toub continues to be overlooked for opportunities. I find it odd that more teams have not explored hiring Patriots offensive coordinator Josh McDaniels, and the film that Bills offensive coordinator Brian Daboll put out last weekend, at the expense of Bill Belichick, should be more than enough to cement his status as an NFL head coach somewhere.

But you never know.

Many of the owners looking for head coaches now have found themselves in this position time and time again, with nothing but losses to show for it. The way these processes are unfolding is already baffling many around the NFL. If you need to talk to upwards of 20 people to find your person, you are probably doing it wrong and didn't do enough research beforehand. The fact that no one has been hired yet is confounding on some levels.

Perhaps it speaks to the level of interest being highest among those who cannot yet be formally hired. And if so, we know where they will be looking. Most of the dots connect back to the same places.