NFL coaches are hired to be fired. Unfortunately, we all know that by now.

This league gobbles them up and spits them out at an alarming rate. It has gotten to the point where many of us have become desensitized to it. Job security is relative and owners have displayed an increasingly fickle nature -- some would say callous -- in how quickly they'll cut a guy loose.

This manifested itself last season beyond the normal turnover in the head coaching ranks -- with guys being fired in October and early November and not just in January, to say nothing of what was an ongoing coordinator carousel. And, of course, the change will continue in 2016. By the end of the season you can expect to see at least six teams looking for answers and maybe as many as 10.

Alas, that's just how this league works in this day and age, with owners more willing than ever to eat huge chunks of money early in a coaching contract in an attempt to get the new "it" guy or someone who better fits their culture, or someone who has worked with their general manager in the past. Oh, the "mutual parting of ways" is probably here to stay.

Of course, this got me to thinking. June in the NFL, if nothing else, allows ample time for navel gazing. And on the heels of my recent column ranking QB tiers, I ruminated on how coaches might most cohesively be clustered in tiers based on job security.

A disclaimer: THIS IS NOT A COACHING RANKING LIST. I AM NOT TRYING TO ARBITRARILY ASSIGN THE "BEST" COACHES IN THE NFL, 1-32.

OK, so with that out of the way, I'm looking at the state of various franchises differently, using the status of the head coach as a portal.

In essence, I want to quantify the pressure cooker these men are in, while acknowledging that with their jobs, every single week from September through January is a mental, physical and emotional wringer unlike most will ever experience. The NFL is the ultimate week-to-week league where, although patience may be a virtue, it is more accurately described as a luxury.

I grappled with whether to start chronicling hot seats from those under the most intense scrutiny to those with the most job security, but after sorting out what made the most sense as tiers, I figured we might as work from the guys on the front burner to those on the back.

Tier 1: Mercury

These guys are closest to the sun, and not because their star is shining the brightest. It's win now or else for many of these guys, and any prolonged skid could lead to talk of in-season replacements in some cases.

Rex Ryan, Bills: The bluster only increased his hot seat, and while the Bills can try to pretend things are harmonious between coaching staff and front office, the turmoil is well known. New ownership needs a decent product at some point, and Terry Pegula has the means to eat a big contract. Mounting injuries to young key players won't help. I wouldn't be surprised if Rex is slaying it sitting behind a TV desk come the playoffs.

Gus Bradley, Jaguars: Owner Shad Khan has displayed tremendous patience, but after a much-heralded offseason this team needs to turn a corner in the standings. Fast. Nominal contract extensions are nice and all, but it's time for results and everyone in this organizations knows it.

Jim Caldwell, Lions: He was left dangling in the wind for weeks last year as the franchise re-organized itself from ownership down. New GM Bob Quinn is a huge fan of Patriots defensive coordinator Matt Patricia, a young coach who would fit the model with a rookie GM. Getting Matthew Stafford -- sans Megatron -- to produce at a level sufficient to save the coach's job may be asking too much.

Rex Ryan's big mouth could cost him his job if the Bills flop in 2016. USATSI

Mike McCoy, Chargers: At one point last season ownership expected to make a coaching change and in the end -- with a potential move to Los Angeles and huge macro issues swirling -- McCoy got a modest extension as the Spanos family goes year-to-year in San Diego. Should the Chargers join the Rams in Inglewood, pressure for a big-name coach could mount. I believe McCoy can get the job done with the right pieces, but are they in place?

Marvin Lewis, Bengals: He has to win a playoff game sometime or a change will be made, right? He has lost a ton of top assistants the past few years and some key players, too. His postseason record could damn him, even though Mike Brown is league's the most patient owner. There have been a series of short-term extensions in recent years.

Bill O'Brien, Texans: A QB guy who has yet to find a passer he could stick with for any discernible period inherits the chore of getting this team back to the playoffs -- and to make Brock Osweiler justify that $38M guaranteed the next two years. Osweiler's contract will make or break O'Brien's tenure, especially after a midseason tear and division title obscured how putrid the Texans were at times the first half of last season.

Jason Garrett, Cowboys: I almost put him in the second tier, but his owner is Jerry Jones, though Stephen Jones, thankfully, seems to be taking the wheel more. Add very high expectations, a healthy Tony Romo and Dez Bryant and an extremely pedestrian NFC East, well, there's a reason this is one of the more high-profile jobs in the league. Jones has already shown more understanding with Garrett than many predicted.

Tier 2: James Brown's Celebrity Hot Tub

Please tell me you remember this Eddie Murphy SNL skit. This is James Brown the late soul singer we're talking about here, not my buddy JB from The NFL Today and, well, as you recall, things can get pretty scalding in these waters. I'm trying not to picture Murphy taking off that robe while these four coaches sit in the tub, donning headsets and all.

Jeff Fisher, Rams: He's a Southern California guy and was hired way back in St. Louis with this move in mind ... but eventually you have to develop an offense of some sort and win some games. And in a tough NFC West with raw rookie Jared Goff at quarterback, that's going to be tough. Fisher, who's in line for an extension, probably ends up getting at least two years in L.A. to finally make this team something at least approximating a playoff contender, but you never know. Stan Kroenke knows one thing -- money -- and he needs to sell a ton of seats and suites.

Chip Kelly, 49ers: The NCAA is always only a phone call away, Santa Clara has become dysfunction junction in the NFL, and you have to wonder how long this marriage lasts after Kelly's carnage in Philly. He doesn't have a QB, or much talent on offense, and I'm not sure this team has even hit rock bottom yet. Two straight one-and-dones would be something, even for San Francisco, but this time it could be the coach and not the team making the call.

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Chip Kelly inherits a huge mess in San Francisco. USATSI

Mike Mularkey, Titans: The new owner showed she wasn't afraid to whack a coach in midseason a year ago, and Mularkey knows the one-and-done drill better than most. He's not exactly the most forward-thinking coach in the league, and if Marcus Mariota isn't amply protected, heads will roll.

Hue Jackson, Browns: You could argue he belongs in the next tier down -- which I will explain in a minute -- but this is Cleveland. That means Jimmy Haslam, which means no one is safe, ever (except for new GM Sashi Brown and his ever-shifting roles in this front office). Jackson isn't exactly a guy who will kowtow to the Harvard coterie calling the shots in football operations. The roster is in shambles and a pink slip is always around the corner in Haslam Country. Few teams have perfected infighting across multiple regimes the way the Browns have.

Tier 3: At least two more years, right?

Things could go south -- or further south -- pretty quickly for some of the guys on this list, but in general this is a spot for first-time NFL coaches and more established coaches entering Year Two of their program. These guys, in all likelihood, will be fine. But would I be totally shocked if one, or maybe even two, of these guys are let go come January? Not in this league.

John Fox, Bears: This team still has a long way to go to be decent. You continue to hear rumblings of things not exactly being all warm and cozy between the coaching staff and front office. The QB is in his walk year. For an older coaching staff, this is likely still a 2-3 year task to truly get this team turned around. Another low-win season and this is worth monitoring at the very least.

Jack Del Rio, Raiders: This wasn't a sexy hire, but Del Rio did a helluva job a year ago. Now with expectations soaring and the owner flirting with a move to Vegas, and with the owner having an ongoing fixation with Jon Gruden (who just lost his broadcast partner at ESPN), and with this, well, still being the Raiders, you just never know. I figure this team pushes for the playoffs and it's a moot point, but this seems like the most appropriate spot to put Del Rio, who some thought wouldn't get another crack at this after he was let go by Jacksonville.

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Expectations are sky high for Jack Del Rio and the Raiders.


Todd Bowles, Jets: He had a tremendous rookie year, though with no QB on the roster and age an issue in some key spots, the Jets could take a step back. Regardless, he isn't going anywhere as he enters his second year in the Big Apple.

Dirk Koetter, Buccaneers: He's a rookie coach who did well with Jameis Winston a year ago and has a potential franchise quarterback on his hands. It's hard to imagine he doesn't get at least a few more years with him.

Doug Pederson, Eagles: With three quarterbacks making starter's money, at least one of them has to be able to play. Law of averages, right? Regardless, next year will be the show-me-something year from second-overall pick Carson Wentz, which gives the new staff at least a two-year cushion one would assume. Then again, no one saw Kelly getting whacked on a Tuesday before the season ended and then shredded by ownership on the way out.

Adam Gase, Miami Dolphins: He's a smart and driven rookie coach who has been saddled with quarterback Ryan Tannehill, for now. This team hasn't won in forever and the locker room has been caustic and cancerous at times in recent years. And they fired pretty much everybody except the guy who drives the team bus in-season a year ago. Gase is going to be there a while and ownership has to know it after the tumult and embarrassment of the Joe Philbin/Dan Campbell regime.

Tier 4: The Newly Empowered

In many of these cases, the coach has just won a tug-of-war of some sort. It could be with the owner. It could be with the general manager. It could be with both. It could be with a (once-considered-potential-franchise) quarterback. It could be they were brought in and handed extreme power while the GM remains under fire. Or they've simply been on the job for a short enough time, and succeeded enough, to the point where it's beyond reasonable to come up with too many scenarios in which this guy could be let go. You could certainly nitpick that one or two of these guys should be in the category above, but to me the status of their GMs (for better or worse) puts them in this even safer tier.

Jay Gruden, Redskins: Potentially the most vulnerable of this bunch should Washington regress widely from its playoff form (which isn't impossible). But he won the RG3 war and managed to keep his job this long despite drawing the ire of Dan Snyder a time or two. That five-year contract helps his cause as well as he enters Year 3. The continued development of Kirk Cousins would only further cement his security. Stud GM Scot McCloughan wants nothing more than to finally establish to continuity in DC.

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Jay Gruden gets some breathing room after a run to the playoffs in 2015. USATSI

Chuck Pagano, Colts: A year ago he would have been leading the list on Mercury, but he survived a down year and a lost season of Andrew Luck and issues with management and an owner who wouldn't offer a legit contract last January. He's emerged more powerful than ever with a much more lucrative long-term deal. After all he went through to make this thing seem Kumbaya back in January, it's be hard to see even Jim Irsay blowing it up a few months later.

Dan Quinn, Falcons: After a torrid start his team fell into a desperate swoon last year, and his offensive coordinator and steeply-compensated QB weren't exactly hitting it off. Once again the fate of GM Thomas Dimitroff also was a topic of conversation. Owner Arthur Blank stood pat yet again after careful deliberation, but with a new stadium on the way and a Super Bowl as well, this team has to turn it around. However, Quinn was given sufficient authority a year ago. If a change is made, one would suspect it comes in the front office, and not at coach.

Ben McAdoo, Giants: He takes over for a very old-school, traditional franchise that stuck with Tom Coughlin for quite some time and it's hard to fathom him going one-and-done here. If anything, GM Jerry Reese is under the heaviest scrutiny, hence the massive spending splurge of this March, which, if it backfires, could have some ramifications for the guys who scout and sign players. But the rookie head coach? Hard to see that.

Mike Zimmer, Vikings: He's done nothing but win and change the culture of this franchise under some extreme duress -- particularly the Adrian Peterson child abuse saga. After years of being passed over for head coaching gigs, he looks like a stalwart in the making.

Tier 5: Granite

So, depending on which science message board you read, granite is pretty much impervious to heat. These are the NFL's made men. They are more or less bulletproof and while some are a little more under the gun than others, these are the top dogs. These are the kind of guys who, even if things do get a little dicey, other teams would be willing to mull trading for.

John Harbaugh, Ravens: Ownership won't tolerate another down year, and things could get interesting in Baltimore with GM Ozzie Newsome seemingly getting closer to retirement. After all the wins and a Lombardi Trophy and being a natural at this, it's hard to fathom this guy anywhere else. The Eagles and others woulda given up a bunch for him last year, I suspect, and he's one of the top half-dozen in the league to me, but two straight down years for an owner who has done nothing but win will put people on edge.

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John Harbaugh is looking to put a terrible 2015 behind him. USATSI

Mike McCarthy, Packers: Similar deal to Harbaugh, with the team not advancing as far in the playoffs recently as fans demand and with an aging but elite GM on board and some succession plan necessary at some point and with this guy already winning a Lombardi. It's hard to imagine him not being there even if other changes come, but fans are demanding a return to glory ASAP and this is undoubtedly one of the best in the world at what he does.

Sean Payton, Saints: Would have been way up the list a year ago as a candidate to move (not be let go), with the Saints not ruling out dealing him and with his contract future in limbo. But the Colts didn't deal for him, he signed a massive new long-term deal with owner Tom Benson, and what was once murky now seems quite clear: he's in New Orleans for the long haul. That is, unless Benson's heirs somehow get their hands on running the franchise (which is quite remote at best). In that case, he and GM Mickey Loomis would be in trouble.

Ron Rivera, Panthers: He just reached the Super Bowl, and has done nothing but win since the shake-up that resulted in GM Marty Hurney losing his job a few years back. He has become a fixture in his community. And he's helping steer Cam Newton to greatness.

Andy Reid, Chiefs: The franchise finally won a playoff game for the first time since the 1992 season and he has been one of the longer consecutively tenured coaches in the league. Ownership loves him and he's as respected by his peers as any coach in the league.

Bruce Arians, Cardinals: This team has become an annual Super Bowl contender under his watch. The players love him, he helps make the long-ignored franchise nationally relevant and he does it all with a unique style. This looks like this could be his gig until he's ready to retire.

Gary Kubiak, Broncos: He just won the Super Bowl despite terrible QB play and his best buddy happens to run the franchise. After a big health scare in Houston, a year as a coordinator seems to have recharged him. He's about as safe as you can be under these circumstances.

Mike Tomlin, Steelers: The Rooneys let go of a coach like once every 30 years, and Tomlin is still quite young (44) and in his prime and not looking to go anywhere. Yes, it's been a while since he's gone on a deep playoff run, but he has won one Super Bowl and been to another ... and this is the Rooneys.

Pete Carroll, Seahawks: He will have a huge new contract before the season begins and works incredibly well with GM John Schneider. This team competes for a Super Bowl every year. He's one of the oldest coaches in the league but also one with boundless energy and enthusiasm and another guy likely to be with his current team for as long as he wants.

Bill Belichick, Patriots: He's the greatest coach of his generation. Does he decide to move to a different role or challenge once Tom Brady retires? Does he want to win a Super Bowl without him? No coach has more authority over an organization and no one has won more since he arrived in New England. He calls the shots.

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Bill Belichick holds all the power in New England. USATSI