Brian Billick and John Harbaugh open up on Bill Belichick, Bruce Arians, Ron Rivera and Gary Kubiak and how the four coaches got to the cusp of Super Bowl 50.

What an intriguing collection of head coaches left standing in the NFL playoffs as we reach the final four stage of the proceedings. Different and yet so alike in many ways. It’s revealing to dive into their stories and their backgrounds to see where they connect and the particulars of how they’ve arrived at this big-stage opportunity.

Three of them are novices in terms of being the head coach in a conference title game, with a shot at the Super Bowl on the line: Arizona’s Bruce Arians won his first career playoff game this past weekend; Carolina’s Ron Rivera his second; Denver’s Gary Kubiak his third.

And then there’s Bill Belichick, the New England mastermind who notched career playoff win No. 23 Saturday night against Kansas City, earning him the right to take a crack at his 10th AFC Championship Game in the past 15 seasons. Consider that Belichick has as many Super Bowl appearances with the Patriots (six) as the other three coaches in this weekend’s field have combined career wins in the postseason.

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Other tidbits I found interesting: Two of the four coaches are old quarterbacks with an offensive pedigree (Kubiak and Arians), while the other two have defensive backgrounds (Rivera and Belichick). Two of them are former NFL players (Rivera and Kubiak) and two of them are career coaches (Belichick and Arians) with no pro playing experience. They’ve all been around awhile in the profession and have similar levels of experience in a matched pair sort of way. Two of them were born less than six months apart in 1952 (Belichick and Arians), and the other two were born less than five months apart in 1961–62 (Kubiak and Rivera).

And this telling nugget, courtesy of ex-Ravens head coach Brian Billick, whom I called Monday for a coaching breakdown of the NFL’s semifinals: All four coaches essentially have been fired once, having bounced back from the searing experience of being told their services were no longer required.

Belichick was canned, of course, as Cleveland’s head coach in early 1996, before the franchise’s move to Baltimore. Rivera was told his contract would not be renewed as Chicago’s defensive coordinator in February 2007, after helping lead the Bears—the team he once played for—to the Super Bowl that very month. Arians was “retired” by the Steelers following the 2011 season after a very successful stint as their offensive coordinator, just before his career renaissance began. And Kubiak was let go as head coach by the Texans in December 2013 after taking the franchise to its first two playoff berths in 2011 and 2012.

Undoubtedly, all four men are who they are as coaches today in some part because of being unwanted elsewhere. Their approaches and their philosophies could not have gone unchanged after those forced separations.

Billick wasn’t the only member of the coaching fraternity I spoke with on Monday regarding an assessment of Belichick, Arians, Kubiak and Rivera. It occurred to me that Baltimore’s current head coach, John Harbaugh, had an almost unique perspective on all four men.

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​Harbaugh served with Rivera as a fellow Eagles assistant on Andy Reid’s staff from 1999 to 2003. He hired Kubiak as Baltimore’s offensive coordinator in 2014, losing him just a year later when Denver hired him to succeed John Fox. He competed against Arians for years in the AFC North when the Ravens-Steelers rivalry was the best the NFL has to offer. And lastly, his coaching battles against Belichick in the upper tier of the AFC have produced some of the most epic playoff games (and particularly AFC title games) in recent memory. If there was one team that has been kryptonite for Belichick’s Patriots dynasty, it has been Harbaugh’s tough-minded Ravens.

Who can match Harbaugh’s well-positioned vantage point in terms of these four coaches and what they bring to the table for this weekend’s two conference title games: No. 2 New England at No. 1 Denver in the AFC, and No. 2 Arizona at No. 1 Carolina in the AFC?

“I think it’s very fitting because when you look at these coaches and their teams, they all deserve to be there,” Harbaugh said by phone, with minor interruptions for helping his daughter through a history-class homework assignment. “These are probably the four best teams, and they followed through and they earned their way there. So I guess the system worked, so to speak. They’re all where they should be.”

After being passed over many times, Rivera has taken advantage of his first head coaching gig. Grant Halverson/Getty Images

Harbaugh’s tie to Carolina’s well-respected Rivera goes back the furthest. They first met when Rivera was a linebacker on the Bears team quarterbacked by John’s brother, Jim Harbaugh. The two were teammates for six seasons, from 1987 to ’92. By ’99, John Harbaugh and Rivera were coaching together in Philadelphia.

“Ron’s a player’s coach, almost a guy who coaches like a player in a lot of ways,” John Harbaugh says. “He’s always looked at things a little differently. He’s always been a guy who’s been unique and always willing to be himself. He’s just a real genuine guy, a real honest guy. He’s the kind of guy who always respects everybody around him. You know it says in the Bible, look at others as being better than yourself, and I kind of think that’s how Ron feels. And yet he’s got this amazing humble confident way about him.”

Rivera’s players revere him for his steady, even-keeled ways and his ability to treat them like men, letting them be themselves while still expecting self-accountability. And after waiting so long for an NFL head coaching opportunity—interviewed nine different times for openings just while he was the Bears’ defensive coordinator—Rivera has obviously grown in the Panthers job, twice rallying to save his job when it was perceived he was in jeopardy of being fired (at the end of the 2012 season and again with Carolina sitting 3-8-1 in late 2014). His Panthers have won 21 of their past 23 games since that low point last season.

“He doesn’t seem like he ever gets too uptight, he kind of goes with the flow,” Harbaugh says. “We were playing Chicago in a playoff game, a divisional game, one year, and all us coaches, we were all sitting in the locker room before the game kind of tapping our toes with our heads down. And we look over and Ron is reading a novel, like just before we go on the field. It was that Dan Brown novel, The Da Vinci Code, just ripping the Catholic church. And Ron’s kind of a devout Catholic, and he’s like, ‘You cannot believe this. This is crazy.’

“[Then Eagles defensive coordinator Jim Johnson] and I looked at each other like, are we about to play a game here?’ Ron’s going to be fine no matter what. He respects his players, he respects his coaches, and he lets them do their thing. And they really respond to him.”

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​Billick remembers doing an early-season Panthers game for FOX in 2012, when there was already widespread speculation that Rivera and his staff were in trouble in just their second year on the job. How Rivera responded to that pressure-cooker situation was telling, Billick said. Carolina started that season 1–6, but rallied to go 6–3 from there, including four wins in a row to finish 7–9 and save his job. The next year, the Panthers went 12–4 and won the NFC South.

“It’s amazing, because they were gone,” Billick recalls. “They were gone, no question about it, and they even thought that. Then they went on a run. And up to that point, Ron had been criticized for not taking chances, so that’s where he really began his Riverboat Ron reputation. He said, ‘O.K., if I’m going down, I’m going to go down with my boots on.

“These four coaches, they’ve all been fired, and that tells you something, too. There’s a perspective there, that being the damaged goods concept, you learn from that, and each would probably tell you that they have.”

Of course, this being the NFL, quarterbacks are always a big part of the reason for a coach’s success. Look at this weekend’s foursome, which features three former No. 1 draft picks in Newton (2011), Arizona’s Carson Palmer (2003) and Denver’s Peyton Manning (1998), as well as that outlier of all outliers, New England’s Tom Brady, who is merely a strong candidate for the title of greatest QB of all time.

“You’ve got two quarterbacks who have moved to another team in Palmer and Manning, and two who have stayed in one place with Newton and Brady,” Billick says. “At the end of the day, what I can tell you about these four teams is they all play good defense and have a quarterback. If you have that, you can cover everything else. You’re going to be O.K.”

Arians’s cut-it-loose style has elevated the Cardinals to contention. John McDonough for SI

In the case of Arians, Billick said his fellow coach has become a sentimental favorite in their fraternity. To get his long-awaited first full-time NFL head-coaching gig at age 60, then nail it, with three consecutive double-digit win seasons in Arizona, it speaks to the go-for-broke mentality he’s known for in calling plays and leading his team.

“He’s obviously a coach’s favorite, because he was a guy who was done, he was heading to the trash heap [after Pittsburgh],” Billick says. “Then all of a sudden he gets resurrected and after a long really good career he gets his chance and he flourishes with it. He’s a guy who calls a game like he’s playing with house money, because he is. It’s ‘I’m going to do it my way,’ and his way is pretty darn good. With Bruce it’s ‘Patience, hell, I’m going to go kill something. We’re going to take some shots.’

“And his players have picked up on it, because his quarterback [Palmer], even if he throws a pick, he just keeps going at it. He’s not going to be daunted and that’s because his head coach is that way. That’s the way the Cardinals play, and they take on that personality, Bruce’s personality.”

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Preparing to play an Arians offense, you know you’re going to get anything but a conservative game plan, Harbaugh said. Arians has worked with quarterbacks like Manning early in his Indianapolis career, Ben Roethlisberger in Pittsburgh, and Andrew Luck in his rookie season with the Colts. Palmer is just another big, strong-armed athletic version of Arians’s prototypical passer, the type of quarterback who is willing to take their chances downfield.

He’s damn the torpedoes, just a supremely confident guy,” Harbaugh says. “And if you’re playing against him, you’re going to make certain assumptions, because he’s going to make every decision to give his players a chance to make plays. With Bruce, it’s kind of Que Sera, Sera. Because when you talk to him, he’s been through a lot of things in life, and he’s had enough things not go his way, where I just think at this stage, he just doesn’t give a damn. And because of it, his guys are filled with confidence.”

That confidence imbues his players with a freedom that other players might not have, Harbaugh said. A freedom from the fear of making mistakes. The Cardinals believe in cutting it loose and not playing scared, because of their risk-happy head coach.

“This guy knows football and is a brilliant offensive coach,” Harbaugh says. “He’s got a great system and he’s got a quarterback he’s absolutely in tune with as far as the way he’s playing. And he’s not afraid to motivate guys. Carson Palmer has been around a long time, and Bruce kind of challenges him to basically go for it, to go make plays. And that’s what I see Carson doing. Some of the the throws he made in our game were just sick throws where he wasn’t afraid to make a mistake.”

Kubiak (left) signed on as Harbaugh’s offensive coordinator after he was fired by the Texans. Charles Krupa/AP

Harbaugh and Kubiak didn’t know each other real well before Harbaugh hired him as offensive coordinator in January 2014, after Jim Caldwell left his staff to take the Lions’ head coaching job. But what Harbaugh learned about the former Texans head coach last year was that Kubiak has a resolve that served him very well this season in the tricky situation he had to navigate in Denver.

“He’s got a unique combination of being staunch in what he believes, especially offensively, and yet he’s very open to people, can relate to people and is just a good guy,” Harbaugh says. “He’s going to do what he believes, but he’s never going to push anything on anybody. He’s got a way about him. He sticks to his guns, but he does it in a way that’s kind of non-combative. He’ll talk you through it and kind of explain it. But he’s not going to be swayed by the wind too much.

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“When I look at Denver’s offense, it’s Gary’s offense. You can see where there are some pieces, O.K., Peyton’s given him some ideas and he’s been able to incorporate them into what he does and so he’s accepted that. But I think he’s done a brilliant job of tying Peyton into what he believes and how he believes in doing it. Pass protection-wise, running game-wise, play-action passes. Those kind of things. It’s all Gary. I’m really impressed with the fact he’s been able to tie that all together. To me it’s because he’s a good guy, with a down-to-earth easy personality.”

Then there’s Belichick, who is impossible to beat, type-cast or summarize in any pithy way, say his fellow coaches. Good luck game-planning for the Patriots, who can reinvent themselves offensively or defensively, seemingly overnight.

“With Belichick, of course, it’s ‘I don’t care,’ ” Billick says. “With him, it’s ‘If we’ve got to throw it 50 times, I’ll throw it 50. And then next week I’ll come back and I’ll run it 50 times on you.’ You never know what you’re going to get.”

With the Patriots and his Ravens having met four times in the playoffs over a six-year span, splitting those games 2–2, which were all in Foxborough, Harbaugh has a better idea than anyone what Kubiak’s Broncos are in for this Sunday in Denver. Baltimore and New England met in both the 2011 and 2012 AFC title games, with the Ravens losing a heartbreaker the first season and then coming back to post a convincing win in 2012, en route to a Super Bowl championship.

“I have just the utmost respect for what he’s done,” Harbaugh says. “You realize how hard it is to have any kind of success in the NFL as a coach or a player, so to see him just doing it over and over again, it’s pretty amazing.”

Bill Belichick and John Harbaugh have squared off in four playoff games, splitting their two AFC Championship Game meetings. Al Tielemans for SI

While you can’t discount the role Brady plays in making up for a multitude of shortcomings that might doom a normal team, it’s the pairing of Brady and Belichick that makes the Patriots the unmatched winning machine they have been for 15 years now, Harbaugh said.

“It’s not enough to just say it’s Brady,” Harbaugh says. “It’s not just him. To me it’s those two guys. Bill is just so good at everything. Game-planning is a big part of it. But how he puts a roster together, how he manages to put the talent in place, around the salary cap, and somehow still maintain the quality of his team is remarkable. He’s always able to re-invent himself, his defense, his offense, from year to year and even week to week. The more you play him against him, the patterns start to emerge somewhat. But then he’s good enough to kind of throw curveballs at you.”

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Like the Patriots did to the Ravens in last year’s AFC divisional playoff at Gillette Stadium, a game Baltimore twice held 14-point leads in but lost 35–31. With his Ravens out of the postseason and enduring a rare down year in 2015, that game is the last taste of the playoffs Harbaugh has had. That game turned in the third quarter, when New England executed a double-pass that saw receiver Julian Edelman—a former college quarterback—throw a 51-yard touchdown to fellow receiver Danny Amendola. It was the first pass of Edelman’s NFL career, and the first non-quarterback pass by a Patriot since 2004.

“Everything is so value-oriented with him,” Harbaugh says of Belichick. “He lets certain guys go that aren’t quite worth the value. He’s always asking, ‘Is it worth it?’ He’ll take chances, like in our game with the trick play, the double pass. Is it worth the risk? Well, he didn’t do it until he had to, but he knew going into the game he felt like he was going to need something. You watch those [documentaries] and he directed [his coaches] to build that kind of play. And that was the perfect time to use it.”

That flexibility of approach and creativity on a week-to-week basis is what makes Belichick the toughest opposing coach in the NFL to beat.

“It takes a ton of fortitude to coach like that,” Harbaugh says. “But I think at this stage of his career, because he’s had so much success, he’s more able to do that. But really, he’s always done it that way. So it’s not just because he’s past worrying what the critics think. He’s never cared what the critics think, and to me that may be his greatest strength.

“But it’s not too hard sometimes to figure out what he’s going to do. We weren’t doing too well in pass defense last year, so we kind of expected him to throw the ball against us. But you better know what your weaknesses are, because whatever your weaknesses are, that’s where he’s coming after you and he’s going to do it in a real creative way. He’s got the quarterback to do it, and he’s got smart players and smart coaches. Hats off to him. It’s a historic thing he’s doing. I don’t care in what profession you’re talking about, it’s historic. I just respect what these four teams have done and what these four coaches have done. They all belong in these games.”