Losing coordinators is NFL's cost of winning. It's a foreign concept for the Detroit Lions

If the Detroit Lions keep winning and winning and even win a playoff game, Ben Johnson and Aaron Glenn will likely be gone. They might be gone even if the Lions don’t win a playoff game.

This is how it goes in the NFL. A team starts winning. General managers notice. The coordinators who helped make winning possible get the chance to lead their own team. Rinse. Repeat.

It's a novel concept around here, though, as Lions’ coordinators don’t get plucked to lead other teams. In fact, it hasn’t happened since before the 1973 season, when offensive line coach Chuck Knox left for the Rams.

That’s 50 years, by my math. Fifty!

Almost too hard to fathom, if we’re being honest. Which makes it surreal that two Lions assistant coaches — TWO!! — will surely get interviews at the end of the season, if the current season stays on track.

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What’s important to know in this situation, since you haven’t experienced it in half a century — which means many of you haven’t experienced it at all — is that this is how the better NFL teams operate: They replace coaches who have left for promotions.

Strange, right?

Not to Dan Campbell. And why would it be? The Lions head coach is himself a product of this system. He worked under one of the best coaches in the league — Sean Payton (this year notwithstanding) — and got his chance.

Now, a couple of his guys might get their chance. Though Campbell isn’t thinking about that just yet.

“Honestly, I haven't gone there yet with that in this moment,” he said.

But?

“I’ve thought about that before. I've thought I was gonna lose A.G. (Aaron Glenn) twice. And Ben (Johnson) last year once. But that was certainly at the end of the year.”

It’s hard to blame him for not wanting to think about it at the moment. His team is rolling. He has a plan to oversee for the Lions' visit to Tampa, Florida, on Sunday. Yet this doesn’t mean he doesn’t have ideas about who could replace his coordinators.

Of course he has. There is no choice. Any head coach who starts to win has to think about the possibility. It’s part of being a head coach.

You know what else is part of being a head coach?

Managing the loss of valuable and talented assistants. The best head coaches do this. It’s where we get the phrase “coaching tree.”

Every long-tenured coach has one. Some more fruitful than others.

The most famous coaching tree in recent days is Bill Belichick’s. His is also the least successful, as Lions’ fans know well. (Hello, Matt Patricia!)

Patricia washed out here in Detroit. Just as almost every other touted assistant of Belichick’s has, wherever they’ve taken over: Eric Mangini, Romeo Crennel, Josh McDaniels — though he’s getting a second chance in Las Vegas — even Nick Saban, who struggled in the pro ranks with Miami before jumping back to college. We could go on. But we won’t, because all of these coaches did stellar work for Belichick.

And all of them were replaced. Yet the Patriots kept winning.

That's the point. Bill Walsh, the groundbreaking offensive coach in San Franciso replaced coordinators and kept winning, building the deepest coaching tree in modern football history. It was a run that included, among others, Mike Holmgren, George Seifert, Mike Shanahan, Jon Gruden, Dennis Green, Brian Billick and Andy Reid.

Reid, of course, has his own branches, both from his days in Philadelphia and Kansas City. John Harbaugh — who is part of Reid’s coaching tree, via the Eagles — has replaced coordinators in Baltimore (drawing from his own and Michigan coach Jim Harbaugh's tree). Just as Mike Tomlin has done in Pittsburgh.

The most famous coaching tree may well be Bill Parcells', in part because he launched Belichick, but also because he developed two other Super Bowl-winning coaches: Payton and Tom Coughlin. That's a lot of trophies.

But, again, the success of coaches after they’ve left their mentors isn’t what matters here. That makes for fun watercooler arguments over résumés and influence. What’s critical is that all of these coaches had to replace talented assistants.

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And did.

And Campbell will, too. At least if he is to become the coach we think he can be.

Obviously, it won’t be easy. Johnson is smart, clever and perfectly in tune with not only Campbell’s offensive vision, but with Jared Goff and the entire offense. Listen to the players — and to the assistants under him — and they describe a budding communicator and visionary who understands everyone’s strengths and how to use them.

Glenn hasn’t generated quite the buzz Johnson has this season, but his defense is starting to turn heads, mostly because of its improvement. If it keeps getting better, Glenn will get more interviews — he already has interviews with the Colts and Saints in previous offseasons — and someone will hire him.

General managers like a good turnaround story. They also like the hire-the-next-wizard story. Both are compelling. Just as both Glenn and Johnson are promising coaches.

Just ask Campbell:

“All I can tell you is they’re both vital to us and our success. And everything … we’ve built. Everybody's got a piece, everybody’s got a job to do, and you want them to be the very best at what they what they’re asked to do. And I feel like we have that. And when you don’t have that, you have to find the right guy that you put in those places when the time comes.”

The time hasn’t come. Not yet. But it will be here faster than anyone thinks, and Campbell understands that. Though he isn’t about to admit his mind might occasionally wander to what life will be like without them, you can bet it has. He’s human.

He’s also showing he has the tools to be the next great program-builder, despite his reluctance to admit that either.

“We’ve got a good program here,” he acknowledged.

Yet?

“I’m not putting that on me. … Everybody’s got a hand in it.”

True, but no one more than Campbell, and to keep this franchise rolling, he’ll likely have to replace at least one critical piece to his program this winter. Because this is what winning NFL franchises do.

Contact Shawn Windsor: 313-222-6487 or swindsor@freepress.com. Follow him @shawnwindsor.

This article originally appeared on Detroit Free Press: Dan Campbell will be ready to replace Aaron Glenn or Ben Johnson